# Check Engine light on no codes show up



## snowwy66 (Nov 5, 2017)

As much as we'd all like.

Replacement parts under warranty don't extend warranty. 

I've yet to see it happen anyways.


----------



## kbarzo (Jan 31, 2016)

Generally, GM parts replacing GM parts by a GM dealer have a 1 year 12,000 mile warranty. Def heater has a longer warranty I believe.


----------



## MRO1791 (Sep 2, 2016)

The generic OBD 2 scan tools won't always be able to read all codes, though it SHOULD if it is emmissions related, as that is a Government Standard for emmissions compliance... If there is an issue with communications on the CAN bus, no reader will gather codes, but it's clear there is a problem if you are in reduced power. Generally the ODB2 connector port will have only 4-5 actual connected wires, +12V, Ground, signal ground (should be same), then CAN H and CAN L. If you have a bad connector pin, or wire to one of these, a code reader can't connect to the car. 

As to the DEF Heater, I do believe that had extended coverage.. I'm trying to log it to verify. 

Ok, found it, Special coverage for the DEF Tank heater, 120K miles, 10 years. See the linked .pdf.. if that is your issue, and you are less than 120K miles, you ar covered for repair at no cost.. though I'm not sure what is going on with your inability to read codes, that is a different issue, but until you have the GM guys not able to read codes, I'm not sure it's a real issue. Who knows about the style of reader at the parts store, or the level of training of the people running the scan... 



https://static.nhtsa.gov/odi/tsbs/2017/MC-10135147-9999.pdf


----------



## DuraCruze2014 (May 26, 2020)

Ok thanks, I'm going to schedule to take a look at the local dealer. Looking at the link as well. I hate the cost just to see what it reads but hey, everyone needs their money.... lol I'll let ya know.


----------



## BDCCruze (Jul 12, 2017)

Yeah, most places like Auto Zone just have skimpy OBDII scanners which are basic servicing. GM specific codes require more advance scan tools. I know O'Reilly's uses a BOSCH scanner which would work on the GM codes.


----------



## DuraCruze2014 (May 26, 2020)

So dealer said it was the exhaust temp sensor #1. There might be more problems after that is fixed he said. He said that code won't let the computer diagnose anything else till its fixed 🤦🏼‍♀️. Fingers crossed this is the only thing.


----------



## BDCCruze (Jul 12, 2017)

DuraCruze2014 said:


> So dealer said it was the exhaust temp sensor #1. There might be more problems after that is fixed he said. He said that code won't let the computer diagnose anything else till its fixed 🤦🏼‍♀️. Fingers crossed this is the only thing.


Well that's not completely true. You can see live data from other sensors. I think what he is trying to say is that the temperature sensor may show "bad" but that may be caused by another issue, not an actual bad sensor. However, they should know that and make sure everything upstream is correct. This is a root cause analysis.

A good example is a O2 sensors. People like replacing them when they get an O2 sensor code, but the code doesn't necessarily mean the sensor is bad it just means what it's reading is outside of the correct range.

Also, make sure they apply the latest ECM updates. The diesels had a few updates a couple years ago that fixes a lot of these sensors going bad in the future.


----------



## DuraCruze2014 (May 26, 2020)

Lovely. Ok thank you, I will make sure to have them do that if they haven't already


----------

