P0171 Error Code - Mechanic Says no Problems

[Litas]

I own a 2013 Sonic LT 1.8L Automatic. The car has had an intermittent rough idle for almost as long as I have had it (about 2 years), and its never seemed to be an issue. Last week when I was driving the car (about 38 mph) the check engine light came on. I didn't notice anything different about the car. The light came on almost immediately after I got a car wash and put oil into the car (87, shell).

I had the code read and it came up as P0171. Took it to a mechanic, and he checked the MAF sensor and for vacuum leaks and found no trouble at all. He cleared the code and didn't charge me a dime. He noted there was a service bulletin out for a possible fuel issue and recommended that I use higher grade gasoline.

About 2 days later the light came on again, about the same speed. I hadn't changed the grade yet as it was still nearly full after the mechanic, so it was running the same gas.

Any ideas what the matter is? My tank is half full with 87 gas, should i fill it with premium? Will the code clear if I do? Any advice would be great. Thanks!

 

[Maddmatts]

P0171 is a code indicating that the engine is experiencing a leaner fuel mixture than what's commanded (too much air or not enough gasoline).

Another option you can try is buying gas at a different station. If you suspect you're running on bad gas, mixing it with good gas is better done sooner than later.

The check engine light will likely persist for several engine start-stop cycles (I don't know the exact number) provided it doesn't detect the same problem in that period. It's quicker to have someone clear the code or disconnect the car's battery for a few minutes (may cause you to loose radio settings).

If the problem still persists, a check of the fuel pump and injectors is the next place I'd look.

 

[rojoes]

Code P0171 you say on a 1.8 litre engine.... hmm sounds like our old nemesis a cracked air intake hose...That is the hose that runs from the air filter box to the throttle body check that hose for cracks....

 

[rojoes]

If it is don't let the dealer charge you too much for the part ... Link for a Chevrolet Dealer that will deliver part to your door for $44.50.....
12 16 Chevy Sonic Genuine GM 94537633 1 8 Engine Air Cleaner Outlet Duct Hose | eBay
Also material used has been changes read my post on this here..Link above is new material
http://www.sonicownersforum.com/for...20387-modified-material-air-intake-house.html

 

[Litas]

Thank you both. Update: I first tried changing the fuel to premium once my tank was closer to empty. After a few days the light went off....until it came back on barely 2 days later. So it wasn't the gas unfortunately.

Code P0171 you say on a 1.8 litre engine.... hmm sounds like our old nemesis a cracked air intake hose...That is the hose that runs from the air filter box to the throttle body check that hose for cracks....

I went and checked the air intake hose (at least I'm pretty sure that's what I saw) and noticed what looks like a small crack. Below is a picture. UPDATE: When my engine cooled off, I put some pressure on the hose and indeed there is a crack, just like the picture above.

One last question:

Is this easy to fix on my own without any special (aka expensive) tools? It looks like it should be, but I don't want to meddle with it if its secretly more complicated hehe.

Thank you!

 

[Maddmatts]

Intake pipes are pretty easy to replace. You usually only need a flat-head screwdriver to undo the clamps on each end. A 5/16" combination wrench or socket should also work.

Just make sure nothing falls into the open intake system while the pipe is off. A little bit of dirt or dust is ok but don't drop any stones or tools in there.

 

[rojoes]

Thank you both. Update: I first tried changing the fuel to premium once my tank was closer to empty. After a few days the light went off....until it came back on barely 2 days later. So it wasn't the gas unfortunately.


I went and checked the air intake hose (at least I'm pretty sure that's what I saw) and noticed what looks like a small crack. Below is a picture. UPDATE: When my engine cooled off, I put some pressure on the hose and indeed there is a crack, just like the picture above.

One last question:

Is this easy to fix on my own without any special (aka expensive) tools? It looks like it should be, but I don't want to meddle with it if its secretly more complicated hehe.

Thank you!

I figured that.... a socket, swivel, extension and ratchet is all you need... I found this link 12 16 Chevy Sonic Genuine GM 94537633 1 8 Engine Air Cleaner Outlet Duct Hose | eBay is is $25.00 dollars cheaper than buying it from local dealer. Note it is shipped to the door cheaper from a dealer in Florida cheaper than my dealer would sell me one. It is an easy fix...As mentioned they changed the material it is made out of so it won't crack again down the road.... Change hose start up and let engine run at least 5 minutes then you can drive the check engine light off or it will be gone next cold start

 

[Litas]

Thank you both! I ordered the updated part on eBay and am going to give replacing it a shot. It seems easy enough. I will post back here to confirm in case anyone else reading these forums is experiencing similar issues. Stay tuned...

 

[Natesriv]

Good deal! DIY always feels best! Especially when it saves you a trip to the dealer and some $$$

 

[Litas]

Update, as promised: Good news! I was able to take out the old air intake hose and replace it with a new one.

Warning to those trying: getting the old one out is a lot harder than it looks. Even after loosening the clamp it is difficult to pull the hose up from the bottom half (the top half came off pretty easily). Because of how cramped everything is in there, I ended up cutting the top half of the old hose off with a razor (very carefully not touching anything else of course!!) and that made it easier to both unscrew the clamp and twist/pull off the hose.

When putting on the new hose, I made the mistake of not checking the placement of the bottom clamp carefully (it was around the wrong portion of the hose just slightly). I had to take it off to make sure the clamp aligned correctly--so be sure to double check before the hose is attached that the clamp is in the right spot. The clamps should be in the groove at each end.

It is day 3 driving and the engine light is off and has not come back on. Engine seems to be running just fine, no more rough idle. Calling it solved! Thanks everyone for the suggestions.

 

[Aftermath86]

I've had the same thing. Rather than install the same part and deal with the same problem over and over again, I went ahead and installed an Injen intake. Got (marginally) better gas mileage and a meaner sound to boot! Its solid aluminum so... it won't crack!