EReali20

About a week ago my Equinox threw a P0172 code.
i am not a person to slack on any type of issue or maintenance with my vehicle. Immediately that night I cleaned the mass air flow sensor (started with the cheapest of suggestions) and that did not cure the light or the dieseling (a term I didn’t realize til I was on plan of attack #3). Also cleaned the throttle body for good measure. At this point I was stumped and spent an entire day researching what this even that was happening was, dieseling or run-on. So per a forum I went and checked the oil for fuel. There was fuel present. I purchased a high pressure fuel pump and replaced that, changed the oil, and changed the air filter while I was at it. I’ve ran seafoam through as well in case the injectors were gummed up. Now immediately after the fuel pump replacement it didn’t diesel for about 2 cycles of on off with the key. But now it’s doing it again but not as bad. I’ve read that you should change the oil a few more times to be sure all the fuel oil mix is out. Does anyone know how long I should wait between oil changes for this particular issue?

side info. I change my oil every 3,000 miles. I drive this thing 25 miles one way to work everyday. I’m meticulous on maintenance and keeping track of it.
my Equinox has 119,000 miles on it.

any advice is welcomed as I feel like I could bash my head on the wall not being able to 100% resolve the issue.

Troger

DId you ever figure out the cause? The dieseling seems like a fairly unique symptom along with that code and I've got a 2015 that's doing the exact same thing with the same code... it tends to go away after a couple of days and then it comes back. It was gone for awhile, but it came back just after I changed the oil.

Thanks,
Troy

oilcanhenry

The answer on the OBD II P0172 fault code, the "dieseling" (trying to keep running after the key is shut off), all are symptomatic of a leaking high pressure fuel pump. The pump leaks into the crankcase, which ends up in the PCV system, resulting in the rich condition AND the dieseling. Rough idle is a result of the rich condition. I hope this helps.

Troger

Super helpful thank you!! Is this a replace the hpfp situation or just tighten down some connections situation?

oilcanhenry

Unfortunately, I am afraid you'll need to replace your high pressure fuel pump. Glad I could help you out, Troger.

comp

did the pump replacement fix it ?

Amaris06

I know this thread is a bit old but I am having the same issues and can't pass emissions. I am trying to avoid extra costs and want to know If replacing the fuel pump will ultimately resolve this issue. I just keep hearing from repair shops and other research that this model has had several issues that always come back. In fact Chevy recalled 2020-2022 models and also 2010-2011 but seem to ignore the years in between with the same issues. A huge nightmare financially.

Any insight or advise greatly appreciated. I filed a claim with NHTSA to be on the safe side because I feel like this should be GM or Chevrolet's responsibility at this point with so many similar issues.