CODE: 171 Recognized a lean burn

[SilverNico]

Sup,

Dealership wanted $75 bucks to read why my check engine light is on. I knew it was SOMETHING with the intake. but not for sure what PART. anyways. I suckered them into doing it for free as 'warrenty work' :)

Results?

CORRECTION: CODE 171 RECOGNIZED A LEAN BURN, POSSIBLE AIR FUEL RATION SENSOR A
COMMENT: NO MAP SENSOR

I have a 5 spd GT w/3rd gen. injen CAI.

does this mean my car is running to lean? Does it mean my MAF sensor is busted? Does it mean if I bought a S-AFC I could fix this myself? (I plan on getting a turbo anyway)

Layman terms! what does it mean?! :P

Thanks a mil!

-Nico

[Blue Bomber]

Here's what the service manual says:

PO171 - System too Lean (Fuel Trim)

DTC Detecting Condition:
When the air-fuel ratio feedback is stable after engine warming up, the fuel trim is considerably in error on the RICH side (2 trip detection logic)

Trouble Area:
Air induction system
Injector blockage
Mass air flow meter
Engine coolant temp. sensor
Fuel pressure
Gas leakage on exhaust system
Open or short in heated oxygen sensor (bank 1 sensor 1)
Heated oxygen sensor (bank 1 sensor 1)It also says the error can be caused by running out of gas.

[RADR1732]

I had the exact same code come up. I work at a shop that specializes in Toyota/Lexus and we have a ECU link-up and pulled the same code. We reffered to the repair manual and found the same thing Blue said. I've had the problem for two months and my car ran like crap. If you recently cleaned your air filter you could have over oiled your filter. If so then you're gonna want to clean your MAFS with an electronic cleaner. I picked some up at CompUSA. Man did it ever make a difference. I car felt a lot better off the line and my fuel milage got better. So far the CEL has not come back on.

Richard

[Griffin]

Originally posted by SilverNico
Sup,

Dealership wanted $75 bucks to read why my check engine light is on. I knew it was SOMETHING with the intake. but not for sure what PART. anyways. I suckered them into doing it for free as 'warrenty work' :)

Results?

CORRECTION: CODE 171 RECOGNIZED A LEAN BURN, POSSIBLE AIR FUEL RATION SENSOR A
COMMENT: NO MAP SENSOR

I have a 5 spd GT w/3rd gen. injen CAI.

does this mean my car is running to lean? Does it mean my MAF sensor is busted? Does it mean if I bought a S-AFC I could fix this myself? (I plan on getting a turbo anyway)

Layman terms! what does it mean?! :P

Thanks a mil!

-Nico


A P0171 indicates that the ECM has had to add total positive fuel trim in excess of 20% Most likely this is due to a MAF reporting an intake value that is falsely low due to a coated element (probably oil & carbon coated) or an intake leak in the CAI somewhere allowing unmetered air to entered. In other words the most likely thing is either there is a loose connection in the CAI or the MAF needs to be cleaned or replaced.

Technically if COULD be a fuel delivery or O2 sensor problem but they are much less common.

As for the comment - no MAP sensor... no ****... this is a MAF engine. Dunno why they wrote that - it doesnt make a lot of sense.

Griffin