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1998 GMC Sierra 2500 5.7L Engine P0172 and P0175 Codes - How to Fix Rich Fuel Mixtures

Model: gmc 2500 Fault Code: P0172 Posted: 2010-02-25 20:00

I own a 1998 GMC Sierra 2500 with a 5.7-liter engine and over 190,000 miles. The truck has recently triggered diagnostic trouble codes P0172 and P0175, indicating that both Bank 1 and Bank 2 are running too rich. I've already replaced the MAF sensor and all oxygen (O2) sensors, but the issue persists. I'm looking for reliable troubleshooting steps to resolve this fuel mixture problem. Any insights or suggestions would be greatly appreciated.

Related fault codes
P0172P0175
Comments (1)
Anonymous 2010-02-26 06:09

Check for a leaking fuel pressure regulator or faulty injectors. Can you scan the O2 sensors and confirm whether they show readings indicating both rich and lean conditions? Also, inspect the exhaust system for any restrictions that might be affecting air-fuel mixture.