P0171 codes

[Salty4Life]

I have a 98 4Runner. Recently changed o2 sensor, upstream abs downstream. I drove the car about 20 miles today and the check engine light turn on. The codes from the scanner are.
P0171 sysytem to lean bank 1
A/Fs or ho2s contaminated deteriorated or system failed, air leaks after MAF sensors or in EGR or PCV system
Fuel control sensor out of calibration
P0130 o2 circuit bank 1 sensor 1
P0133 o2 sensor circuit slow response bank sensor 1

I’m gonna clean the MAP sensor and see if that helps, but the p0130 code was the one that made me change out o2 sensors and it’s still popping up. Now it says circuit one bank one.

Does anyone have any advice on what else to try?

 

[jgue467]

If air intake tubes are original, there is a good chance the closest one to the metal plenum has a crack and is leaking air in, messing up the A/F mixure.

Since it has lots of folds, the cracks hide there. I replaced mine with OEM when i got an 0171, gone since. Now the part number on the pic is for an 01-02, so get the one specific for your model, I'd suggest OEM.

Luck.

 

[brillo_76]

+1 on that air intake hose from maf to intake. I had one Crack.

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[octanejunkie]

Clean the MAF sensor with sensor cleaner and make sure your filter element is clean and free of debris.

Like has been said, make sure there are no air leaks between the MAF sensor and the throttle body.

Check all vacuum hoses in and exiting the engine bay, like to the vacuum can in the driver's wheel well.

Silly question, has the truck ever just fallen out of cruise control for no apparent reason?

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[gamefreakgc]

P0130 and P0133 only show up if you have an issue with the front O2 sensor or the wiring. Inspect the wiring harness from the sensor to the main engine harness and look for damage or melting - it is very close to the exhaust. If it checks out, you might have got a dud of a sensor and try another.

P0171 could be a vacuum leak. Clean the MAF sensor first though.

 

[Salty4Life]

Cleaned the MAF sensors, and checked all vacuum lines. I disconnected the battery to clear the codes. Drove around today and the lights haven’t come back on. It’s just strange that the MAF sensor can throw that many codes

 

[octanejunkie]

Cleaned the MAF sensors, and checked all vacuum lines. I disconnected the battery to clear the codes. Drove around today and the lights haven’t come back on. It’s just strange that the MAF sensor can throw that many codes

Cool.

Get a code scanner, they are not super expensive and worth owning when you drive a 20+ year old truck. Plus you can clear the codes easily and not have to disco the battery for 30+ mins (which also resets the entire ECU, fuel tables, clock and radio presets) to clear a code.

Completing a drive cycle will be the real barometer of whether the issue is resolved or not. Here is an easy read on how to do that:

How to Complete a Drive Cycle | YourMechanic Advice

Make sure your fuel tank is at 50% full or so for the EV test to complete, that one takes the longest.

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[Salty4Life]

Cleaning the MAF sensors and re checking all the vacuum lines fixed it. Thanks yall