Reply to PO 171 Condition

Here is someone 's comment on the 171 condtion:

PO 171 condition means there is too much oxygen entering the system.

Start at the air filter box and check everything for air leaks and disconnected or cracked air hoses all the way through the induction system.

Check every electrical connector for poor connection and solid grounding. Check because sometimes they look okay but are loose inside and when reattached a wire inside may simply be pushed back instead of actually connecting and you get shorting or intermittent problems from engine vibration.

Another techique is to shoot propane at suspected leak/open points. If the engine runs faster when spaying the propane, the leak is there.
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QUOTE=ltsNkaty;3932582]2000 Avalon
At 93,000 miles ………..
Check engine light came on when accelerating to get on freeway.
Also had check engine light about a month before that - occurred when accelerating to get on freeway. Went to AutoZone to check the error code which was P0171 (air/fuel lean bank 1 or low fuel pressure or faulty MAF/VAF sensor or cylinder misfire condition or faulty H02S/AF sensor or large vacuum leak). Reset the error code which has just reoccurred.
The rest of the story ………………
At 81,000 miles had the check engine light. Took car to dealer – P0171 error code, system too lean. Dealer completed a “peak of performance fuel system service”, parts – “EFI, TB, & TEC Kit”.
And, at 57,000 miles had the check engine light. Took car to dealer – performed “peak of performance service” (flushed fuel injectors, top engine clean & decarbonize, and clean & decarbonize throttle body). Sounds like the same service that was done at 81,000 miles.
I guess I will take it back to the dealer for service. ??
Suggestions or comments?
[/QUOTE]

 

Dealer's not helping you.
Clean the MAF sensor wires and the 171 should go away.

 

DIRTY

 

CLEAN

 

23 August 2012

Thanks to maun and csaxon for providing the solution to my problem.

Checked vacuum lines and connections - all OK.

Cleaned MAF sensor, cleared the error code.
Test drive and no check engine light!

Thanks again.

Regards,
ltsNkaty :thanks:

 

23 August 2012

Thanks to maun and csaxon for providing the solution to my problem.

Checked vacuum lines and connections - all OK.

Cleaned MAF sensor, cleared the error code.
Test drive and no check engine light!

Thanks again.

Regards,
ltsNkaty :thanks:

How do you check and clean MAF SENSOR

 

Glad to help.

 

I tested resistance on my 2000 Avalon MAF sensor and it checked out at 2.55 K at 68F.
I then checked voltage between VG and E2G When engine was cold the minimum was 1.84 VDC at idle and revved up 2.10 VDC after running for a few minutes the engine speed lowered and the minimum voltage dropped to 1.4 and the max revved up was 2.3 V Does amyone know if that is enough change to verify the MAF is working properly? This seems like a small change.

 

According to the manual, as long as it fluctuates, then that is satisfactory. The ECU is measuring the amount of amperage flowing through the sensor to keep it at the target temperature. The voltage change is just an result of the voltage drop as resistance and current changes. It's not measuring anything from the voltage.

 

After replacing MAF Sensor and other O2 sensors without any luck I thought I would try a new gas cap. BINGO Check Engine Light has been off for a couple of months. 188K miles on this 2000 XLS Avalon.