P0171 and P0496

[Casual Observer]

Hey all,

I drive a 2015 Chevy Sonic 1.8L. I had noticed the engine had been running a bit rough the last few days and this morning I popped those two engine codes, P0171 and P0496. I'm just starting to do my research before I dig in and take a look at it but I will update this with my progress as I go along in case anyone else has similar issues.

The P0171 seems to be a very common one for this car, seems like a vacuum line has a tendency to break so I'll be looking for that.

Symptoms (perhaps related perhaps not)
-Engine running a little rough, shifting timing is a bit off, probably related to the rough running engine.
-Slight amount of foamy gunk in the oil filler cap, seems to be coolant maybe water, tan/brown in color.
-Engine tick, although this seems to be normal for the model
-Belt noise when the car revs above around 3K, slight burning rubber smell. I guess that it might be a tensioner not quite keeping up.

Again I will update as I figure it out, any ideas or suggestions would be welcome, thanks guy and gals!

 

[Casual Observer]

Update Time!

So I checked the usual suspects for a vacuum leak and couldn't locate any obvious issues. I filled the gas tank and have a tough time starting the car immediately afterwards and it felt like it was about to stall out once I began driving.

I did some more research and stumbled across a few different people with that same issue saying it was a bad canister purge valve for the evap system. It's in an easy enough spot that I figured I'd buy a new one and at least pull the old one off and check it. It's supposed to be closed when there is no power to it and then it opens when energized. I pulled the old one off and low and behold it was stuck open.

Two hoses and one electrical plug late the new one was in, I erased the code and 150 miles later it has yet to return and the motor is running MUCH smoother. I was kinda shocked something like that would have that dramatic of an effect but now I know! Hopefully this helps some one else with a similar issue.

 

[BlurRS]

Very nice! I actually had this issue with my 2.2 ecotec when I still had it. Couldn’t for the life of me figure it out. I was told that overfilling or “topping off” the gas tank causes these issues when more than just vapor makes its way towards the canister.

 

[dannyg]

I also have a 2015 1.8L, glad to hear you got it fixed. Just curious, how many miles on the car? Im up to 38K...not much. Thanks.

 

[JTee2017]

The 2014 Sonic we have in the family had about 73,000 miles before the purge solenoid went bad on it. $28 and 15 minutes replacing it did the trick.

 

[Casual Observer]

I also have a 2015 1.8L, glad to hear you got it fixed. Just curious, how many miles on the car? Im up to 38K...not much. Thanks.

38! She's still a baby! I had 57,000 miles on it when it occurred. I must admit I top off the fuel quite a bit so if that does indeed contribute to a solenoid failure then yup I did that haha.

 

[dannyg]

38! She's still a baby! I had 57,000 miles on it when it occurred. I must admit I top off the fuel quite a bit so if that does indeed contribute to a solenoid failure then yup I did that haha.

She’ll be five in February awwwww!

Thanks for the info. I’m keeping up on maintenance and won’t panic if I get a purge or thermo issue!

 

[JackGSonic]

Glad to find this post. My 2015 turbo started throwing these codes yesterday and today. Looks like I'll be ordering a new valve.