Engine running like crap codes 122, 157, 172, 181, 186, 189, 556?

230,000 MILES • 4.0L • 4WD • AUTOMATIC
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JOHN STARKEY
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  • 2 POSTS
Obd1 scanner codes 122, 157, 172, 181, 186, 189, 556. Hard starts, stalling, works better with maf unplugged, runs ok until heated up, then dies, air at fuel rail
Oct 14, 2026 at 2:02 PM
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STRAILER
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  • 55,694 POSTS
So these codes come up when the engine has a vacuum leak or the fuel filter is clogged.

122 Throttle position sensor signal too low
157 Mass airflow sensor signal too low
172 Oxygen sensor indicates a lean condition
181 / 189 Lean condition during part-throttle operation
186 Injector pulse width higher than expected
556 Fuel pump relay primary/control circuit fault

Here is the location of the fuel filter and a video and how to change it, with a video on how to check for a vacuum leak.

https://www.youtube.com/watch?v=xN5pcM-5bso

and

https://www.youtube.com/watch?v=tym7gO9RlxE

Please check the intake tube between the MAF sensor and throttle body, there should be no cracks/tears.
Oct 14, 2026 at 5:50 PM
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