What about your flex pipe? Have a good look at it with a mirror. Mine pops the code once every 3 months. I've got the black suit on the collar of the pipe. I know it's leaking, just been neglecting to get her done.
Check engine light for P0420 Catalyst System Efficiency Below Threshold (Bank 1)
I keep getting a check engine light code for P0420 Catalyst System Efficiency Below Threshold (Bank 1) on a 2016 Chevy Trax. I change both O2 sensors out and even the Catalytic convert. I went with Certified GM parts to replace the bad parts with. I can reset the code but it comes back with in a day or so. The frist convert fail due to the engine misfiring. I also replaced the spark plugs and the coil pack because of the misfiring. Does anyone have any experience or suggestions on this?
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It maybe it. It was broke and I had it replace when the Catalytic converter went out the 1st time. Maybe they didnt weld it right or something. I am on my 2nd converter. I was thinking my air to fuel ratio is not right somehow or have a leak some where.
I have been having the same issues with my 2016. Replaced the converter, both oxygen sensors, flex pipe, map sensor, maf sensor, coil pack, plugs, had the smoke test done for evap leaks and nothing was found. I'm beyond furious with this Trax not knowing what it is. It's not so much the engine light that bothers but the periodic slight hesitation on acceleration. Any tips would be helpful but I'm at the point of selling it. I refuse to pour thousands of dollars into a car just to have the same issue again
Sounds like the same problem because i replaced every you did and did the same test. But i didnt have the acceleration issue. Chevy needs to get to a major over haul on the 1.4 Ecotec engines in general. After 100,000 miles. They break down fast. My family in the pass had nothing but issue with that engine. Not with the manufacturer.
About my Trax i had to get rid of it/ trade it in becuase one day after work it just completely die on me. I had 130,000 miles on my Trax. I Lost power and all of my Electronics after About 30 mins of sitting on the side of road it restart and drove fine home. That was my last straw. At the dealership. I didnt tell them, the engine shut off but the mechanic told me it chould be the timing belt(dont what this has to do with the 420 code) they wear out about 100,000 miles or so or he siad something with the brain of your is not right. Not communicating with the other parts of the car. So possibly a new Wiring harness. Both are 2,000 to 3,000 to fix. Hopefully thats helps?
About my Trax i had to get rid of it/ trade it in becuase one day after work it just completely die on me. I had 130,000 miles on my Trax. I Lost power and all of my Electronics after About 30 mins of sitting on the side of road it restart and drove fine home. That was my last straw. At the dealership. I didnt tell them, the engine shut off but the mechanic told me it chould be the timing belt(dont what this has to do with the 420 code) they wear out about 100,000 miles or so or he siad something with the brain of your is not right. Not communicating with the other parts of the car. So possibly a new Wiring harness. Both are 2,000 to 3,000 to fix. Hopefully thats helps?
Mine just hit 89k. 2nd owner and it has always been serviced on time. I know there is a special bulletin for the turbo but nothing for the converter. Chevy has really gone down hill over the years. I love the car but it's not worth the money going into it 😤
I have the same P0420 code at about 115K miles on my 2015 TRAX. I am the original owner and the vehicle has been serviced regularly with no major issues. I can clear the check engine light but the code stays stored in the ECU. I was able to totally clear the code out by spraying the end of the upstream O2 sensor with cleaner and spraying some cleaner into the sensor hole directly into the cat. Unfortunately, the code came back after a few days and about 50 miles of driving. I have not experienced and negative driving symptoms.
I've done a fair amount of research and it appears that a bad cat or O2 sensor(s) are the most likely causes, followed by an exhaust leak between the header and cat (flex pipe). I haven't gotten under the car to check for a leak yet.
Does anyone have any suggestions for troubleshooting that does not involve replacing parts? I feel like I'm overlooking something, especially since I was able to clear the code once, even if temporarily.
I can share this link which has some pretty good insight into what may be going on:
I've done a fair amount of research and it appears that a bad cat or O2 sensor(s) are the most likely causes, followed by an exhaust leak between the header and cat (flex pipe). I haven't gotten under the car to check for a leak yet.
Does anyone have any suggestions for troubleshooting that does not involve replacing parts? I feel like I'm overlooking something, especially since I was able to clear the code once, even if temporarily.
I can share this link which has some pretty good insight into what may be going on:
P0420 caused by bad O2 sensor?
P0420 — Is it the catalytic converter or the oxygen sensor?
ricksfreeautorepairadvice.com
I'm at a dead end with this. I have searched online for causes, symptoms and suggested repairs and everything has been done. After replacing the cat and both oxygen sensors the light literally came back on when I was driving home from the shop. Took it back multiple times and nothing. They even did the smoke test for an evap leak and found nothing. It's the slight hesitation on acceleration that is bothering me. If something isn't figured out soon this Trax is going up for sale. I'd rather take a loss from what I already have into it than keep pouring more money into repairs that aren't going to fix the problem
Did they smoke test your exhaust?
From what I was told they did but with these shops now a days who knows. I do hear what seems to be a slight exhaust leak towards the front and it does have an exhaust smell but they say they didn't find anything. When the flex pipe was replaced I see they applied extra weld around it but one thing I did notice is that they used one that was half the size of the original. I don't know if that would cause any issues though
My mechanic cuts out the old flex pipe, puts in the new and tacks it in. Then he removes the pipe from the turbo and CAT and brings it on the bench to do a seamless weld right around. It doesn't leak once he's done. Did my daughter's Encore and soon to do mine. Pull along side a brick building and bring down your window, if you hear exhaust that's your P0420, either bring it back to get it done right or go to a real muffler shop.
The flex pipe was actually done at a shop that only deals with exhausts. My mind is boggled right now because of this. Last I was told is that maybe the converter was defective. If there is anyone near Ft. Lauderdale Florida area that knows what they're doing and can diagnose it that would be great
Hi, I'm new to this forum but not to the P0420 code.Does anyone have any suggestions for troubleshooting that does not involve replacing parts? I feel like I'm overlooking something, especially since I was able to clear the code once, even if temporarily.
I can share this link which has some pretty good insight into what may be going on:
P0420 caused by bad O2 sensor?
P0420 — Is it the catalytic converter or the oxygen sensor?ricksfreeautorepairadvice.com
Yes, there is an awesome thread covering this code:
P0420 Diagnosis
There are several reasons a P0420 will come up as an error and illuminate the MIL. A lot of people are scared of it. They get all excited and search all over the internet to try and guess at what they should do. Reading good advice and bad trying to save money and hoping it's not a Catalytic...
www.subaruoutback.org
The thread is huge, thousands of posts. It explains how the P0420 code should be diagnosed. Read at least the first 20 to 50 or so posts and you'll get a much better idea what the code means and how to cure it. Most of the time, the cat is NOT the problem. The real problem can be as simple as bad gas, a bad thermostat or worn spark plugs and wires.
Some info is specific to subarus but most isn't.
Good luck!
Sent from my SM-G781U using Tapatalk
I am currently sorting out a P0420 on a 2015 Trax with 141,000 miles on the odometer. For the sake of keeping all the info in one place, I will continue on this thread, although it is old-ish.
Seeing as no one here seems to have resolved the issue, I'd like to at least report my method and results since I am the one actually doing the work on the vehicle and I'm using the factory service manual.
SYPMTOMS: None! Except for a pesky MIL. Great acceleration, ECU is not pulling any timing or fuel to manage the poor catalyst efficiency.
DIAGNOSIS
Paraphrasing, here's what I've done so far:
-I am using a Snap-On Solus edge and the factory service manual to diagnose.
-I have watched the data on both HO2 sensors and they are good.
-I have visually inspected the flex pipe and it has no leaks or visible failure. The entire exhaust system was removed and cleaned due to a failed turbo pouring oil down the exhaust. Visually and mechanically it was all sound.
-I have witnessed the 'catalyst monitor test' result in "FAILED" via the Solus. The test and data performed exactly as described by the manual to obtain that result.
The manual then says:
"DIAGNOSTIC INFORMATION AND PROCEDURES > DTC P0420: CATALYST
SYSTEM LOW EFFICIENCY > CIRCUIT/SYSTEM TESTING
Verify the conditions listed below do not exist with the catalytic converter(s):
1. Dents
2. Severe discoloration caused by excessive temperatures
3. Road damage
4. Internal rattles caused by damaged catalyst substrate
5. Restrictions
If a condition is found: Replace the catalytic converter.
If no condition is found:
Verify the conditions listed below do not exist with the exhaust system:
1. Leaks
2. Physical damage
3. Loose or missing hardware
If a condition is found: Repair or replace the component as necessary.
If no condition is found:
Verify the conditions listed below do not exist with the B52B Heated Oxygen Sensor 2:
1. Incorrect torque
2. Damage
If a condition is found: Replace the B52B Heated Oxygen Sensor 2 or repair the condition as necessary.
If no condition is found
1. Replace the exhaust front pipe and the warm up three-way catalytic converter.
NOTE: A new converter with less than 100mi on it may set the P0420 DTC due to outgassing of the internal matting. Operating the vehicle at highway speeds for approximately 1 hour may correct the condition."
NEXT STEP
I have no conditions that I was able to find in any of the above. I will be replacing the catalytic converter as my next step. This ultimately makes sense in my situation as I purchased the car with a failed turbo and it had soaked the entire intake tract, hoses, intercooler, and exhaust with oil. Watch for a follow up post as soon as my converter arrives.
Seeing as no one here seems to have resolved the issue, I'd like to at least report my method and results since I am the one actually doing the work on the vehicle and I'm using the factory service manual.
SYPMTOMS: None! Except for a pesky MIL. Great acceleration, ECU is not pulling any timing or fuel to manage the poor catalyst efficiency.
DIAGNOSIS
Paraphrasing, here's what I've done so far:
-I am using a Snap-On Solus edge and the factory service manual to diagnose.
-I have watched the data on both HO2 sensors and they are good.
-I have visually inspected the flex pipe and it has no leaks or visible failure. The entire exhaust system was removed and cleaned due to a failed turbo pouring oil down the exhaust. Visually and mechanically it was all sound.
-I have witnessed the 'catalyst monitor test' result in "FAILED" via the Solus. The test and data performed exactly as described by the manual to obtain that result.
The manual then says:
"DIAGNOSTIC INFORMATION AND PROCEDURES > DTC P0420: CATALYST
SYSTEM LOW EFFICIENCY > CIRCUIT/SYSTEM TESTING
Verify the conditions listed below do not exist with the catalytic converter(s):
1. Dents
2. Severe discoloration caused by excessive temperatures
3. Road damage
4. Internal rattles caused by damaged catalyst substrate
5. Restrictions
If a condition is found: Replace the catalytic converter.
If no condition is found:
Verify the conditions listed below do not exist with the exhaust system:
1. Leaks
2. Physical damage
3. Loose or missing hardware
If a condition is found: Repair or replace the component as necessary.
If no condition is found:
Verify the conditions listed below do not exist with the B52B Heated Oxygen Sensor 2:
1. Incorrect torque
2. Damage
If a condition is found: Replace the B52B Heated Oxygen Sensor 2 or repair the condition as necessary.
If no condition is found
1. Replace the exhaust front pipe and the warm up three-way catalytic converter.
NOTE: A new converter with less than 100mi on it may set the P0420 DTC due to outgassing of the internal matting. Operating the vehicle at highway speeds for approximately 1 hour may correct the condition."
NEXT STEP
I have no conditions that I was able to find in any of the above. I will be replacing the catalytic converter as my next step. This ultimately makes sense in my situation as I purchased the car with a failed turbo and it had soaked the entire intake tract, hoses, intercooler, and exhaust with oil. Watch for a follow up post as soon as my converter arrives.
Update!
My Magnaflow "direct fit" catalytic converter showed up and has since been installed. It fit like garbage (mounting bracket holes were over 1/2" off in all three dimensions). I was able to bend the brackets on the converter enough to mount and test it. I ran the three-way-converter monitor test a total of 8 times resulting in 'PASSED' twice, after a few 'NO DECISION's.
I almost always go with OEM on my repairs but the cheapest I could find the GM converter was $950ish plus $400 core charge. I got the Magnaflow with a 20% coupon for $650ish and I'll get to scrap the original converter. Be warned trying to go with Magnaflow's converter. I love there builder grade products where I do the welding and the fitment for custom exhausts. Really unhappy to see such a poor fitting product from them.
I'm considering my P0420 resolved. I don't imagine I will receive the code again because every the test had run before it resulted in 'FAILED'. Ill put some mileage on it to verify this week.
My Magnaflow "direct fit" catalytic converter showed up and has since been installed. It fit like garbage (mounting bracket holes were over 1/2" off in all three dimensions). I was able to bend the brackets on the converter enough to mount and test it. I ran the three-way-converter monitor test a total of 8 times resulting in 'PASSED' twice, after a few 'NO DECISION's.
I almost always go with OEM on my repairs but the cheapest I could find the GM converter was $950ish plus $400 core charge. I got the Magnaflow with a 20% coupon for $650ish and I'll get to scrap the original converter. Be warned trying to go with Magnaflow's converter. I love there builder grade products where I do the welding and the fitment for custom exhausts. Really unhappy to see such a poor fitting product from them.
I'm considering my P0420 resolved. I don't imagine I will receive the code again because every the test had run before it resulted in 'FAILED'. Ill put some mileage on it to verify this week.
Literally same. 2015 Trax. Fixed my turbo, cat, spark plugs, O2 sensors, pcv manifold… EVERYTHING. CODE STILL COMES BACK ON. And also sometimes hesitation with acceleration. This was all fixed after i broke down on the interstate. I took it back to the shop today, I’ll let you know if they come up with anything new.I'm at a dead end with this. I have searched online for causes, symptoms and suggested repairs and everything has been done. After replacing the cat and both oxygen sensors the light literally came back on when I was driving home from the shop. Took it back multiple times and nothing. They even did the smoke test for an evap leak and found nothing. It's the slight hesitation on acceleration that is bothering me. If something isn't figured out soon this Trax is going up for sale. I'd rather take a loss from what I already have into it than keep pouring more money into repairs that aren't going to fix the problem
I am still code free and seem to be one of few who have resolved this. If you can be more specific on what "fixed" means for each of the parts you addressed, I may be able to help identify what was missed or potentially done incorrectly (i.e. did you repair or replace a certain part? Why? And how/with what?). Ultimately, unless your ECU or wiring harness is damaged (this is extremely unlikely), something isn't "fixed" correctly. I highly recommend purchasing the factory service manual. That is what I used and I was able to follow step by step to identify the issues. I just took the exhaust system back apart to replace my oil cooler gaskets and was able to verify all of my repairs are holding up for the P0420 code. Have you verified everything you replaced? It is possible for a new part to not be working correctly. Unlikely, but possible.Literally same. 2015 Trax. Fixed my turbo, cat, spark plugs, O2 sensors, pcv manifold… EVERYTHING. CODE STILL COMES BACK ON. And also sometimes hesitation with acceleration. This was all fixed after i broke down on the interstate. I took it back to the shop today, I’ll let you know if they come up with anything new.
common mistakes:
-O2 sensors MUST be OEM (and must be the correct part numbers: there are two different upstream/bank 1 O2 sensors for these engines and I believe they both fit. Use your VIN when ordering).
-Vacuum system MUST be completely sealed.
-Check your flex pipe with a flashlight. It can be easy to mis small cracks/tears.
-Who is resetting your codes and how are they doing it? They need to be able to read live data with a scan tool. There is no other way to perform a complete test of the electronics that are impacting that code. In other words, a code reader is not sufficient.
-The factory service manual states that your code may still return for approximately the first 100 miles because the new materials are off-gassing/breaking in as they heat cycle for the first few times. Don't panic if the code comes on after a new catalytic converter. Drive it for 100 miles, reset the code, and see if it comes back.
I suspect something is wrong with your vacuum system or in your intake system (everything from MAF to manifold) if you are having poor acceleration. That may not be related to the code and may be a separate issue.
I am still code free and seem to be one of few who have resolved this. If you can be more specific on what "fixed" means for each of the parts you addressed, I may be able to help identify what was missed or potentially done incorrectly (i.e. did you repair or replace a certain part? Why? And how/with what?). Ultimately, unless your ECU or wiring harness is damaged (this is extremely unlikely), something isn't "fixed" correctly. I highly recommend purchasing the factory service manual. That is what I used and I was able to follow step by step to identify the issues. I just took the exhaust system back apart to replace my oil cooler gaskets and was able to verify all of my repairs are holding up for the P0420 code. Have you verified everything you replaced? It is possible for a new part to not be working correctly. Unlikely, but possible.
common mistakes:
-O2 sensors MUST be OEM (and must be the correct part numbers: there are two different upstream/bank 1 O2 sensors for these engines and I believe they both fit. Use your VIN when ordering).
-Vacuum system MUST be completely sealed.
-Check your flex pipe with a flashlight. It can be easy to mis small cracks/tears.
-Who is resetting your codes and how are they doing it? They need to be able to read live data with a scan tool. There is no other way to perform a complete test of the electronics that are impacting that code. In other words, a code reader is not sufficient.
-The factory service manual states that your code may still return for approximately the first 100 miles because the new materials are off-gassing/breaking in as they heat cycle for the first few times. Don't panic if the code comes on after a new catalytic converter. Drive it for 100 miles, reset the code, and see if it comes back.
I suspect something is wrong with your vacuum system or in your intake system (everything from MAF to manifold) if you are having poor acceleration. That may not be related to the code and may be a separate issue.
By fixed , i meant the shop replaced these items. So I’m not sure exactly what kind of parts specifically. The acceleration isn’t too too bad or noticeable unless for a split second on the highway. The cause of all of this was me breaking down on the highway.I am still code free and seem to be one of few who have resolved this. If you can be more specific on what "fixed" means for each of the parts you addressed, I may be able to help identify what was missed or potentially done incorrectly (i.e. did you repair or replace a certain part? Why? And how/with what?). Ultimately, unless your ECU or wiring harness is damaged (this is extremely unlikely), something isn't "fixed" correctly. I highly recommend purchasing the factory service manual. That is what I used and I was able to follow step by step to identify the issues. I just took the exhaust system back apart to replace my oil cooler gaskets and was able to verify all of my repairs are holding up for the P0420 code. Have you verified everything you replaced? It is possible for a new part to not be working correctly. Unlikely, but possible.
common mistakes:
-O2 sensors MUST be OEM (and must be the correct part numbers: there are two different upstream/bank 1 O2 sensors for these engines and I believe they both fit. Use your VIN when ordering).
-Vacuum system MUST be completely sealed.
-Check your flex pipe with a flashlight. It can be easy to mis small cracks/tears.
-Who is resetting your codes and how are they doing it? They need to be able to read live data with a scan tool. There is no other way to perform a complete test of the electronics that are impacting that code. In other words, a code reader is not sufficient.
-The factory service manual states that your code may still return for approximately the first 100 miles because the new materials are off-gassing/breaking in as they heat cycle for the first few times. Don't panic if the code comes on after a new catalytic converter. Drive it for 100 miles, reset the code, and see if it comes back.
I suspect something is wrong with your vacuum system or in your intake system (everything from MAF to manifold) if you are having poor acceleration. That may not be related to the code and may be a separate issue.
They also updated my PCMBy fixed , i meant the shop replaced these items. So I’m not sure exactly what kind of parts specifically. The acceleration isn’t too too bad or noticeable unless for a split second on the highway. The cause of all of this was me breaking down on the highway.
If the shop you go to is not telling you why and how they repaired something, that's a huge red flag. Also, if they aren't showing you where in the factory service manual flowchart for diagnosis it calls for that repair, that is an even bigger red flag. If you can get specific information from them (like the results of all the tests the manual says to perform) I am happy to share my diagnosis of your car.
What are the O2 sensor mV readings per the scantool during the test conditions?
What is the 3-way warm-up converter test outputting during the test conditions: Passed? Failed? Undecided?
Has the turbo been removed and inspected?
Are there any leaks into the turbo or the intake manifold?
I hope I'm not coming across condescending; I'm genuinely trying to offer help. I am trying to illustrate the significance of having your car repaired correctly and there's only one way to do that: follow the manual verbatim, please! The manual will tell you exactly what to do, how to do it, and when to do it. If your shop is not following that, and if they do not know it well enough to explain it to you and have you understand, find a new shop. This should be a really easy fix for a full service shop.
What are the O2 sensor mV readings per the scantool during the test conditions?
What is the 3-way warm-up converter test outputting during the test conditions: Passed? Failed? Undecided?
Has the turbo been removed and inspected?
Are there any leaks into the turbo or the intake manifold?
I hope I'm not coming across condescending; I'm genuinely trying to offer help. I am trying to illustrate the significance of having your car repaired correctly and there's only one way to do that: follow the manual verbatim, please! The manual will tell you exactly what to do, how to do it, and when to do it. If your shop is not following that, and if they do not know it well enough to explain it to you and have you understand, find a new shop. This should be a really easy fix for a full service shop.
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