So this afternoon my wife was driving and the check engine light came on. She got home and checked the code and got P0171. She cleared the code and ran other errands. On her way back home she got the CEL again and now it pulled codes P0171, p0300, p0301, p0302, p0303 and p0304.

Before we start throwing parts at the car (plugs and ignition coils) we are thinking that we might have gotten a bad tank of gas. Tomorrow morning I am going to check all vacuum hoses, clean the MAF sensor, change the oil and check anything else under the hood.

Would a bad tank of gas cause all these codes? She's got about half a tank so we are going to fill it up with non-ethanol gas and put some octane booster/cleaner in the tank and see what happens.

If none of the above work, we will start with the plugs and then move to the coils.

any other thoughts or suggestions on the route to go? Any personal experiences with all these codes at the same time and what you did to fix them? I've searching through Google but nothing ever mentions that it could be a bad tank of gas. She just filled up two days ago and now these codes so that's why we are leaning towards bad gas.

Thanks guys!

 

New update. Changed the oil, changed the air filter, cleaned the MAF sensor and checked and cleaned all of the spark plugs. The car ran fine for about an hour and then it sat for about 4 hours. We got back in the car and starting driving home and about half way home the check engine light came back on and starting running rough. We are going to change the spark plugs tomorrow and see what happens since they probably need to be changed anyways. Could it be the coils?

I am going to call Monday to see if it qualifies for the recall and see if they will replace the coils.

Any other thoughts on what's going on?

BTW...the CEL is on solid, NOT flashing and the hestation/missing only happens at idle. There is no missing when the car is under any acceleration (around town or interstate).

Need some heip, need to have car running by monday. I've searched throught about 300 posts and think it could be the coils but want to try cheaper opyions first.

 

Nobody? Nobody has any thoughts or possible fixes? Yes, I searched and read through about 300 posts last night but nothing seemed to answer my specific questions.

I unplugged the MAF sensor and it seemed to run a little rough but never through another check engine light after we cleared the others. Does that mean that the MAF sensor is good?

 

I have the exact same problem.. Pulled codes P0300-P0304, P0171.. CEL was on solid with some rough idle.. after a week or two the idle became more rough and the CEL flashes occasionally at idle.

- I've replaced all spark plugs and coils; didn't help at all.
- Replaced air filter and cleaned out the MAF/throttle body.. Ran MUCH smoother and flashing CEL ceased.. after driving 30 min it returned at idle.
- Found a leak on the pancake valve/PRV/boost control valve, whatever you'd like to call it... when I covered the leak the idle smoothed significantly so I sealed it w/epoxy just to test it.. Seems to idle even more rough now.

If you figured it out please post what you did/tried to resolve it, i've got an appointment to take it in on Friday but am going to pick up a new PRV/pancake valve and replace that tonight.

Thanks much and hope your prob got resolved.

 

I'm new to the forum. i pulled the same codes as above - i don't see any answers to the questions - am i not reading this blog right or ddi no one actually answer with a solution? I don't mind bringing it into the dealer but I'd like to get an idea of what I am in for interms of cost, and nature of repair.

Thank you in advance for your replies!

 

P0171 I believe is the air injection... Check your secondary air pump... Its located below the air box... Disconnect it an plug it back in... If it doesn work it may have gone out... But the p0300-p304 is the cylinders... Check coils if not coils it could be the silinoid... An also check the wires(harness) that conect to the coils...

 

I spoke to someone else on these forums who had the exact same issue and they fixed all the codes by replacing the PCV on their B7, i've got a B6 and found a leak on my PCV so i'm picking the part up at the dealer today and will post results once replaced.

With the P0171 check for any cracked hoses or air leaks.. Also try running it with your MAF sensor unplugged, it may be a dirty or bad sensor..

Start your car, listen for any air leaks.. take some carb cleaner and start spraying the hoses & valves.. if you hear the engine start singing a different tune then you found your leak.. I'd start w/your PCV *aka boost control valve, pressure regulating valve, PRV, pancake valve, pressure control valve*... Here's a picture and PN for B6 is 06A-129-101-C replaced by F and B7 is 06F129101L,C,F,K,N.
My B6 PCV with Epoxy smeared on it:


*Tip* since you are receiving P0300-P0304 its probably not a bad spark plug or coil since ALL of them are reporting misfires... the P0171 can most definitely cause the P300-304 codes though..focus on that.