p-0171 keeps coming back

**RyanL** · 12-28-2010

hey so for the past month i keep getting this damn code p-0171 system too lean bank 1. the car has 140 000km on it and doesnt seem to be taking too much gas. the code comes and goes but when it does come back it only happens during cold start up. I changed the o2 sensor thought that was the problem. it was good for a week and now came back. so what do you think could be causing this. it is a jobber part not an original. all my gaskets have been changed within a year so im not burning any oil or coolant or what not. the maf had been changed also what else could be causing this?

**TheOtherNick** · 12-28-2010

do you have an exhaust leak?

**RyanL** · 12-28-2010

only a small leak in a muffler so not related.

**01gpgt01** · 12-28-2010

vac leak

**OrangeL67** · 12-28-2010

Do you ever run octane booster? When I put octane booster in to run my 3.1 pulley, I usually see that same code if I have a quarter tank or less. It goes away if I add more gas.

**RyanL** · 12-29-2010

No just running regular gas.

**01gpgt01** · 12-29-2010

ocane booster makes you run rich. I see my AFR go from 11.8 to 11.5 when I run it.

**zildjian102** · 12-29-2010

When i had that code turned out my throttle body gasket was bad

**rynoman03** · 12-29-2010

^^ I've had this happen as well.

**RyanL** · 12-30-2010

Il check the gasket but it was changed about 6 months ago. For the vacuum leak il check it but I don't think that's it.

**RyanL** · 12-30-2010

ok so no leak from the throttle body sprayed brake cleaner all around it while the engine was running and nothing at all. so now i guess for the vacuum, where exactly are the other vacuum hoses i only saw on on the pcv valve

**01gpgt01** · 12-30-2010

the entire UIM and LIM Vac hoses. They can be tough to find

**Kejross** · 12-31-2010

Vac is my guess as well... Just diagnosed a truck with MAF DTC's and turned up cracked vac fittings.

**RyanL** · 01-04-2011

Just found a cracked vacuum hose after the pcv valve. I fixed it up cleared the code and will let u guys know if it comes back. This thing was on and off everyday so if it doesn't comeback in a week I think that's it. Didn't see any other problems with the vacuum hoses. But thanks for the help il let u guys know how it goes

**Kejross** · 01-04-2011

I love it when they are that simple...

**RyanL** · 01-04-2011

if it could only be that easy all the time.

**Kejross** · 01-04-2011

I just ordered all new blue silicone hoses to redo mine, the one under the snout of my blower keeps popping off now that its colder and pushing more boost. Hate vac lines/leaks!!

**BillBoost37** · 01-05-2011

I've found P0171 to be a few different things.

Evap backwards: Luckily the W bodies were redesigned and didn't get the same crappy hookups to the evap system as the H bodies. However it's possible the evap hoses at the soleniod were mixed up during work.

Corroded battery cables: If the corrosion is bad enough, it'll mess with the voltages a bit and throw the code.

Vacuum leaks: A very common leak is the EGR tube that leads from the EGR to the LIM. It's nearly impossible to spray with cleaner and get a reaction. Yet if you pull it and look where the piece that holds it to the LIM sits...you'll usually find a crack in it.