My RL and the persistent CEL...

[Project_ION_1]

I was getting seemingly random CELs that would last for a few runs and then one time when I would start the car up it wouldn't be there. Then after about 20 minutes it came back. Car ran fine I thought. So I took it to the dealership and they came back with:

CUSTOMER STATED THE SERVICE ENGINE LIGHT IS ON
TECHNICIAN VERIFIED THE CONCERN WITH CODE DTCP0171
SET IN CONTROLLER TECHNICIAN RESET ALL CONTROLLERS
TEST DROVE THE CAR & CODE DID NOT RESET

Came in on a Saturday, so I didn't really get to talk to anyone and the receptionist didn't know anything. I read that is was Fuel Trim Level Lean Bank 1...?

Can someone ecplain that to me? I figure it probably means I was running lean. Anyone know anything more than that?

[S.Bretz]

Means it was reading lean under cruising and couldnt bring it to stoich. COuld be o2 sensor acting up...could be low fuel pressure. Could be a few things. I'll check the computer tomorrow (if I remember) and report back how to possibly fix it.

[Project_ION_1]

Means it was reading lean under cruising and couldnt bring it to stoich. COuld be o2 sensor acting up...could be low fuel pressure. Could be a few things. I'll check the computer tomorrow (if I remember) and report back how to possibly fix it.

Thanks a ton for your input. It hasn't kicked back on yet though, so hopefully it will be okay.

[LowSL2]

Well if the ecotec is similar to the 2002 dohc, this is what my FSM says.

Diagnostic Aids

DTC P0171 indicates the engine is running lean. The following are possible causes of a lean air/fuel mixture:

- Vacuum leak
- Fuel pressure low
- Fuel quality poor or water in fuel
- Exhaust manifold gasket leak or leak around O2S-1
- Fuel injectors clogged
- O2S-1 weak

To verify the system is running lean, use Scan tool to monitor O2S-1 and HO2S-2. If both sensors are below 300mV, the system is running lean and the oxygen sensors are probably not at fault.

[Project_ION_1]

Thanks for all the info. Thankfully, it has not kicked back on yet. I have a feeling that it is probably either fuel pressure or clogged injectors. Car sometimes feels a little hesitent. I am gonna get some cleaner to send through the car, and if it lights again, I am just gonna take it back to the dealer again.

[therealm0rh0us]

its an 04?
if so i would say theres a slim chance of a vacuum leak or a line was knocked off by someone doing service but if the light has been off for a while you may want to check the upstream o2 and like you said run cleaners thru it
maybe a botched gasket from the factory
get a can of ether and spray it where the intake man meets the head and see if the idle changes
im goin to get another beer

[Project_ION_1]

its an 04?
if so i would say theres a slim chance of a vacuum leak or a line was knocked off by someone doing service but if the light has been off for a while you may want to check the upstream o2 and like you said run cleaners thru it
maybe a botched gasket from the factory
get a can of ether and spray it where the intake man meets the head and see if the idle changes
im goin to get another beer

Thanks for the info, I will give it go...

[therealm0rh0us]

when?

[Project_ION_1]

Well, since the check-up at the dealer, I have no had the problems since. I also through some injector cleaner in the tank. Seems like everything is running great again...