2017 L5P with P20EE code

[chessy56]

2017 Silverado, L5P w/81K miles. Starting to get code P20EE which suggests a "low catalyst efficiency". I can clear the code with my Edge and drive for a certain number of miles without the code reappearing- but, it eventually returns. I've seen some owners claim the #2 NOx sensor or the DEF injector may be the culprit.

Question: is there a problem driving this thing in the near term without major problems? I can force a "mobile regen" via my Edge, so I believe my DPF is being serviced. Maybe a flakey NOx sensor? A carboned/dirty DEF injector nozzle?

Where on the exhaust stream are these injectors and sensors physically mounted (any pics/diagrams) available? Any thoughts or suggestions?
Thanks!

[DmaxMaverick]

The NOx sensor and DEF are not related to the "catalyst" monitoring. They deal with NOx alone. An O2 or temp sensor, or failed Cat is more likely. The sensors can read erroneously before they actually fail enough to cause complaints. Start by removing your electronic power mods (completely, not just disabled). Diagnostics with it/them in place will have you (and the PCM) chasing wild geese.

[chessy56]

For what it's worth, the P20EE code is no longer appearing and the check engine indicator has reset itself. I'm currently not reading any DTC codes. I recall having this failure long before I reached the first 30K miles. I had the dealer's tech look into this and there were no active codes for him to work from at that time either.

A temp or O2 sensor was mentioned- I've forced 2 "mobile regens" now (with my Edge) and the exhaust temps came up to what I've seen before. Problem appears to be hidden again, unless the sensors are indeed flaky.

Thanks Maverick!

[DmaxMaverick]

An off-the-cuff thought is an O2 sensor. Not necessarily failed or failing, but possibly being plugged. This has been an issue, often intermittent, since they showed up on vehicles. There's usually an underlying cause, such as a "rich" condition (as it applies to gassers), or overfueling (as it applies to Diesels with a failed charge-air system, or power mods). A completed regen may explain the disappearance, with the soot cooked out of the sensor. A sensor that's out of range, but not enough for the system to see it as a failed sensor, often causes the PCM to assume an erroneous condition. It doesn't mean that something is actually broken, only that the PCM isn't getting the data it expects. That's my best guess.

[Kennedy]

For what it's worth, the P20EE code is no longer appearing and the check engine indicator has reset itself. I'm currently not reading any DTC codes. I recall having this failure long before I reached the first 30K miles. I had the dealer's tech look into this and there were no active codes for him to work from at that time either.

A temp or O2 sensor was mentioned- I've forced 2 "mobile regens" now (with my Edge) and the exhaust temps came up to what I've seen before. Problem appears to be hidden again, unless the sensors are indeed flaky.

Thanks Maverick!

Are you monitoring soot levels?

Are you monitoring miles since last regen?

[cabletech]

There is a recall associated with P20EE on the 17 & early 18 L5P trucks. Have you had the recall (ECM/TCM programing) done? That code is related to an NOx issue. The programing also addressed some odd 2nd to 1st shifting issues. Also soot levels are in percentage, not grams of soot as was used on previous models.
FYI there are no oxygen sensors on the L5P diesel.

Jay

[chessy56]

I am not monitoring soot levels. I'd have to check my edge, but I don't recall seeing a PID for that (is that a monitored variable that is available on a Tech II or EFI Live?). And while I do see the mobile regen occurring on occasion, I have not been paying attention to the miles in between. Probably a good idea to be doing so.

As to the recall on the P20EE, I wasn't aware of any and logging into the MyChevy site, there's nothing listed for recalls on my '17 Silverado. However, I had been dogging the dealership on a P140B code. I was getting that code when driving in heavy rain or if my induction system ingested a bunch of snow. GM finally resolved that problem and the most recent flash supposedly covered several updates. The P20EE may have been one of the issues addressed.

I got the P20EE a couple of times when my truck was still under warranty, but the problem was always cleared by the time my dealer tech looked at it. Until recently, I hadn't had this code in nearly 60K miles.
Thanks guys!
Gary

[DmaxMaverick]

You should still be under warranty. Either the 100K Diesel engine warranty, or the emission system warranty (varies, depending on state and RPO).

[chessy56]

The dealership hosed me over $100 to have my PCM flashed a few weeks ago. I called Chevy customer disservice and bitched, as I thought the flash addressed a failure which involved the emission system- which I thought was covered under warranty until 5 yr/100K miles. They told me that reflashing the PCM was "not covered under warranty", given the 79K miles I had on the truck at that time. They're claiming they'll cover the drive train and any mechanical failures on the engine, but not reprogramming! I asked to speak to the district manager and I was told to take it up with the dealership.

Thank you Mary Barra for reducing the warranty coverage on these trucks. That L5P cost me a lot more than the old LB7 I used to have and the warranty on my '01 was better than what I've got now.

[DmaxMaverick]

Any calibration installed to address a valid drivetrain or emission system complaint is absolutely covered by the warranty(ies). At the very least, the emission system warranty. If a calibration was installed to correct an otherwise warranty covered complaint, then the calibration was covered. Did the calibration installation correct anything you complained about? Did you ask for it, not related to a valid complaint? If not, they're still on the hook for it.

[chessy56]

The P140B got to the point of being repeatable. After complaining to my dealership, my technician did a little investigating and found that GM admitted that there was a problem- but at the time, a fix was not available. I checked back after a couple of months and was informed that a fix had been found and that an update flash would be required to resolve the issue. I don't believe there was any "recall" on this issue- I asked for the newest flash. My argument was that the fault involved the emission system, it was a known defect to GM (a design flaw in their calibrations) and therefore, it should've been GM's responsibility to correct it. Not to mention that when this code surfaced, the CE lamp would light and my remote start capability was defeated. Since the new flash, I have not seen the P140B return as of this writing and I've been in heavy snow and rain (at highway speeds) where it often surfaced. It wasn't that my EGR valve was "slow to respond"- it was more like my air filter was partially clogged by moisture which inhibited air flow. Rain/Snow or otherwise, once the moisture dried out, no further P140B codes were generated.

If there's a possibility that my truck's warranty should've covered this flash, is there someone other than the turds at Chevy Customer Disservice that I can plead my case to? There used to be district managers that we could take our issues to- do they still exist? Are GM representatives still monitoring these pages like they used to?

Thanks again for allowing me to vent!
Gary

[cabletech]

Here is the recall. I have the pdf file but it's too big to upload.I would be glad to send it to you if you want it.

Jay

Product Emission Recall
17337 Diesel Particulate Matter Sensor Diagnostic Fault
Copyright 2018 General Motors. All Rights Reserved. Page 1 of 4
Reference Number:
N172118140
Release Date:
January 2018
Revision:
02
Revision Description:
This recall is being revised to update the Attention box because all phases have been released, and to update the Service Procedure section to clarify the OAT sensor learn. Please discard all previous copies of bulletin 17337-01.
Attention:
This Product Emission Recall was released in phases:
• Phase 1 includes certain 2017-2018 model year Chevrolet Silverado HD and GMC Sierra HD vehicles.
• Phase 2 includes certain 2016-2018 model year Chevrolet Colorado and GMC Canyon, 2017 model year Chevrolet Cruze, and 2017 model year Chevrolet Express and GMC Savana vehicles.
• Phase 3 includes certain 2018 model year Chevrolet Cruze and Equinox, and GMC Terrain vehicles.
Make
Model
Model Year
RPO
Description
From
To
Chevrolet
Colorado
2016
2018
LWN
Engine-Diesel, 2.8L
Cruze
2017
2018
LH7
Engine-Diesel, 1.6L
Express
2017
2017
LWN
Engine-Diesel, 2.8L
Equinox
2018
2018
LH7
Engine-Diesel, 1.6L
Silverado HD
2017
2018
L5P
Engine-Diesel, 6.6L
GMC
Canyon
2016
2018
LWN
Engine-Diesel, 2.8L
Savana
2017
2017
LWN
Engine-Diesel, 2.8L
Sierra HD
2017
2018
L5P
Engine-Diesel, 6.6L
Terrain
2018
2018
LH7
Engine-Diesel, 1.6L
Involved vehicles are marked “open” on the Investigate Vehicle History screen in GM Global Warranty Management system. This site should always be checked to confirm vehicle involvement prior to beginning any required inspections and/or repairs.
Condition
General Motors has decided to conduct a Voluntary Emission Recall involving certain 2016 model year Chevrolet Colorado, GMC Canyon; 2017 model year Chevrolet Express, GMC Savana; 2017-2018 model year Chevrolet Colorado, Cruze, Silverado HD, GMC Canyon, Sierra HD and 2018 model year Chevrolet Equinox, GMC Terrain vehicles, equipped with a diesel engine. The engine control module in these vehicles may not properly diagnose a fault in the exhaust particulate matter sensor.
Additionally, a subset of these vehicles, certain 2017 model year Chevrolet Silverado HD and GM Sierra HD vehicles, may in rare instances exhibit a condition in which the engine surges up to 2,800 RPM during vehicle coast or vehicle braking.
Correction
Program the engine control module, and transmission control module when applicable.
Parts
No parts are required for this repair.
Warranty Information
Labor Operation
Description
Labor Time
Trans. Type
Net Item
9102933 *
Engine Control Module Reprogramming with SPS (Phase 2-3)
0.3
ZFAT
N/A
Add: To Relearn OAT Sensor (Colorado/Canyon Only) (Phase 2)
0.2
9102934 *
Engine Control Module and Transmission Control Module Reprogramming with SPS (2017-2018 Chevrolet Silverado HD and 2017-2018 GMC Sierra HD only) (Phase 1)
0.7
ZFAT
N/A
9103390 **
Module Programming Not Required (Phase 1-3)
0.2
ZFAT
N/A
* To avoid warranty transaction rejections, the SPS Warranty Claim Code must be entered when submitting this transaction.
** SPS

[DmaxMaverick]

The P140B got to the point of being repeatable. After complaining to my dealership, my technician did a little investigating and found that GM admitted that there was a problem- but at the time, a fix was not available. I checked back after a couple of months and was informed that a fix had been found and that an update flash would be required to resolve the issue. I don't believe there was any "recall" on this issue- I asked for the newest flash. My argument was that the fault involved the emission system, it was a known defect to GM (a design flaw in their calibrations) and therefore, it should've been GM's responsibility to correct it. Not to mention that when this code surfaced, the CE lamp would light and my remote start capability was defeated. Since the new flash, I have not seen the P140B return as of this writing and I've been in heavy snow and rain (at highway speeds) where it often surfaced. It wasn't that my EGR valve was "slow to respond"- it was more like my air filter was partially clogged by moisture which inhibited air flow. Rain/Snow or otherwise, once the moisture dried out, no further P140B codes were generated.

If there's a possibility that my truck's warranty should've covered this flash, is there someone other than the turds at Chevy Customer Disservice that I can plead my case to? There used to be district managers that we could take our issues to- do they still exist? Are GM representatives still monitoring these pages like they used to?

Thanks again for allowing me to vent!
Gary

If your dealer won't help, contact GM Customer Care. Request a reimbursement for service you paid for that is now covered under a recall, and reference the TSB # posted by Cabletech. It should be only that simple, but keep calling if necessary.

[chessy56]

I'll try GM Customer Care, but it will take a few days as I'm heading out for some outdoor's time. Will reply after my return. Thanks!

[chessy56]

Well, I called GM customer care and was told that my 2017 2500HD is only covered up to 50K miles on the emission system. The "drive train", presumably the engine and transmission, are good up to 100K or 5 years.

After looking at the TSB that Cabletech had listed out (thanks Cabletech!), the bulletin addressed a Diesel Particulate Matter sensor- apparently not associated with the P140B code I was receiving. I do recall however, that my PCM was flashed better than a year earlier for a matter related to a DPF sensor and I was not charged for that re-flash (my service manager tossed that one in given the amount of $$$ I spent at this dealership over the previous years).

As to the P140B condition, GM won't budge. They state that all TSBs are "vehicle specific" and unless a specific component used in my particular truck is a known problem, they won't warranty the repair. They're holding firm to the 50K mile warranty limitation on the emission system. Which really SUCKS given that I'm now seeing multiple codes/indicators that are related to the emissions again. My take away: GM doesn't stand behind their product like they used to. But they'll gladly take your money for another new vehicle!

If anyone has additional thoughts, I'll welcome them. Seems like I'm getting no where with GM

[rapidoxidationman]

One thought would be to see if you qualify for a return. Looks like you have a 3 year window to do so, if the truck gave you enough trouble in the first year.
https://wisconsindot.gov/Documents/d...onlawafter.pdf

[chessy56]

Thanks for the tip regarding the lemon law. After looking this over, I'd have to admit that I wouldn't qualify-
Within the 1st year, there wasn't "a" particular problem condition that required the service dept to attempt a fix 4 or more times to resolve. Nor was the truck out of service for 30 or more days during that 1st year.

I've been in the shop several times in the last 2 years for about 6 different error conditions, but none meet the 2 criteria above. What particularly sucks is that sensors are very expensive, GM reduced their warranty coverage on these trucks and even after 2+ years, GM's ability to stock some replacement parts for these trucks is questionable.

My latest problem that involves the EGR system speaks to the issue of a lack of replacement connectors, given that several folks nation wide are experiencing the same problem. People are looking for them- not a one to be found anywhere. I doubt GM will take notice.

Thanks for the consideration just the same .