Trouble Code 157 MAF | Ford Explorer Forums - Serious Explorations

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Trouble Code 157 MAF

Harry P

April 2, 2002
Reaction score
City, State
Harleysville, PA
Year, Model & Trim Level
94 XLT 4x4
CEL came on last week, and idle became rough.

KOEO: Code 111 (No faults on KOEO). I only get one CM Code 157 (Mass Air Flow signal is/was low or grounded – MAF). No other codes.

I took it out. It appeared fine, not dirty. I cleaned it with spray solvent. Put it back in, no change. I still get CEL and rough idle, and no additional codes.

Ex has 177k miles and the MAF has never been replaced. I recall taking it out to clean it six or seven years ago to solve the same code then.

What’s the next step? Should I buy a new MAF?

Thanks, Harry

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Get a can of Mass Air Flow cleaner.

Yep. I cleaned it. What's the next logical step?

check the output voltage

You can test the MAF sensor (MAFS) by backprobing the connector pins with straight pins and then measuring the outputs with a voltmeter at various engine speeds. From the code you can't tell if the MAFS output is low at idle or fast engine speeds. If the output is low at idle then your engine will run lean.