Causes of an intermittent P0171 ?

[TRD 4RNR]

What else should I be looking at as the potential cause of an intermittent P0171 (the yellow check engine light goes on & off every couple of days)

I have a ScanGauge - anything I can check with it to help get to the bottom of this?

Supercharged
CA emissions (w/dual cats)

- I've cleaned the MAF
- Using a Toyota Paper Air Filter
- Replaced both the AF & O2 sensor (with Denso)

Thank you and Happy New Year

 

[Skulking]

What else should I be looking at as the potential cause of an intermittent P0171 (the yellow check engine light goes on & off every couple of days)

- I've cleaned the MAF
- Using a Toyota Paper Air Filter
- Replaced both the AF & O2 sensor
(CA emissions w/ dual cats)

Thank you and Happy New Year

Lean could mean a leak. Inspect your hoses for damage, and if you want, you can spray something flammable like carb cleaner around the various hoses listening for the RPM to change to try and track down the source of the leak.

 

[heat]

The big throttle body hoses can/do crack and/or the clamps get loose over time.

If you haven't already, use only Denso sensors. Aftermarket ones often just
don't work. I chased this code, and it took longer because the replacement
non/Denso rear O2 sensor was off. Replaced it with the original eventually. My
problem turned out to be the front A/F sensor.

 

[FD7683]

You can use a smoke machine for the hoses to see if one is leaking. Very handy tool to have/use.

 

[TRD 4RNR]

The big throttle body hoses can/do crack and/or the clamps get loose over time.

If you haven't already, use only Denso sensors. Aftermarket ones often just
don't work. I chased this code, and it took longer because the replacement
non/Denso rear O2 sensor was off. Replaced it with the original eventually. My
problem turned out to be the front A/F sensor.

I used Denso
I'll check for cracks and/or loose clamps.
Might be time for a smoke machine.

Thank you

 

[jgue467]

Here is the cause of an 0171 on mine, largest air intake 'hose' nearest intake had a crack that could only be seen if pulled apart just a hair yet the leak was there regardless, went OEM and smilin' since!

 

[shadow247]

Here is the cause of an 0171 on mine, largest air intake 'hose' nearest intake had a crack that could only be seen if pulled apart just a hair yet the leak was there regardless, went OEM and smilin' since!

I just did this over the weekend, along with the A/C idler pulley. What a world of difference it made in the power and sound. I was about to start troubleshooting a phantom miss at idle, but the Boot was the cause of all my issues!

 

[TRD 4RNR]

Here is the cause of an 0171 on mine, largest air intake 'hose' nearest intake had a crack that could only be seen if pulled apart just a hair yet the leak was there regardless, went OEM and smilin' since!

[MENTION=75316]jgue467[/MENTION]
I bought the part in your post and went to install it today and found the hole in the side to be much larger in the new one. Should I have ordered something different? Or do I need a different plug?

Thanks

 

[spartacus]

[MENTION=75316]jgue467[/MENTION]
I bought the part in your post and went to install it today and found the hole in the side to be much larger in the new one. Should I have ordered something different? Or do I need a different plug?

Thanks

They have different air cleaner hoses for build date.

17882-62010 5VZFE..VZN18* (07/1998 - 07/2000)

17882-62020 5VZFE..VZN18* (08/2000 - )