Check Engine Light Code 25
 

The check engine light came on tonight. No problems after driving it home. I got only one code: 25. I reset the check engine light, then turned on the engine. The code returned. Haynes says air-fuel ration lean malfunction. How should I proceed to identify the problem? Thanks

Any other codes besides this one?

Thanks.

Only 25.

This is a system code causing a lean A/F ratio. Need to start checking items that can cause this.

Does the engine idle and run OK? If so check the following first:

Bad O2 sensor or wiring.
Coolant temp sensor for computer or wiring. Can check resistance.
Intake air temp sensor or wiring. Ditto.
Intake air or vacuum hose leakage (might start here).
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If not also check the following:
Fuel issues causing a lean mixture.
Ign issues.

thanks!