How do you figure out why the check engine light keeps coming on?
20

Asked by GuruNQF53 Jun 19, 2022 at 04:00 PM about the 2004 Ford Expedition

Question type: Maintenance & Repair

I have a used 2004 Expedition, the check engine light was on, change out
the spark plugs (when doing so there were 5 different types of plugs!), and
changed the ignitions coils (there were 4 different types of these!) Engine
light was still on
so far I have changed
Spark plugs
Ignition coils
Mass airflow
PCV valve
Fuel Filter
used gas additive
codes were erased, check engine light went off.
About a week after replacing the mass airflow filter the check engine light
came back on.  I thought now I will know what the real problem is, went to
auto zone run the code reader.  The only thing that came up was the mass
airflow filter!
With a brand new mass air flow filter, one would think that was not the
problem.

6 Answers
2,870

VRoom12345 answered about a year ago

Most times a Mass air flow code is not the unit itself that is the issue and no need to replace it. What is the 4 digit code?

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155,365

james answered about a year ago

What code do you have? It could be the wiring going to the MAF and not the sensor itself. Hope that helps! Jim

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james answered about a year ago

P0171 is a lean air to fuel mixture on the side of the engine where cylinder number one is. C1175 is the left rear wheel speed sensor circuit failure. The circuit is either open or shorted. So neither code is for the MAF. The P0171 could be a vacuum leak, intake manifold leak, exhaust system leak, cracked exhaust manifold, or bad oxygen sensor. You need to concentrate your efforts on the side of the engine where the number one cylinder is. The C1175 code is pretty self explanatory. Hope that helps! Jim

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