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2004 Tahoe P0171 P0174 O2 Sensor & MAF Issues at 334,000 Miles

Model: 04 tahoe Fault Code: P0171 Posted: 2018-05-06 19:45

My 2004 Chevrolet Tahoe is showing trouble codes P0171 (Rich Fuel Mix - Bank 1) and P0174 (Rich Fuel Mix - Bank 2), along with intermittent P0300 (Random Misfire). I also experience MAF sensor circuit malfunctions. The vehicle has reached 334,000 miles and exhibits sluggish acceleration—especially during takeoff—until it reaches 2nd or 3rd gear. Occasionally, power returns briefly when accelerating, but the engine runs sluggishly until throttle is applied. O2 sensor readings drop to low values after acceleration begins. I've already replaced the MAF sensor, but the codes persist. It appears someone previously removed the oxygen sensors during a repair, which may be contributing to the issue. I suspect a vacuum leak, as positive fuel trim values normalize at higher RPMs. I'm planning to replace the manifold gasket soon and would appreciate advice on affordable, reliable parts—GM's quoted price is $88 for a set. Any recommendations on bolt types or grommets that are durable and cost-effective? Thanks for any insights.

Related fault codes
P0171P0174
Comments (5)
Anonymous 2018-05-06 21:38

Start by diagnosing the MAF sensor malfunction, as it may be the root cause of the P0171, P0176, and P0300 codes. Many users report that addressing the MAF circuit resolves multiple related issues in this vehicle model.

Anonymous 2018-05-07 07:01

I replaced my MAF sensor earlier, but I forgot to mention that someone previously removed the oxygen sensors during a repair. This could be causing the fuel trim imbalance and erratic engine behavior. The vehicle whines when accelerating and feels sluggish until it reaches 2nd or 3rd gear. Power returns briefly when I press the gas pedal, then drops again—O2 sensor readings go from high to low under load.

Anonymous 2018-05-07 07:40

A vacuum leak is a likely cause if positive fuel trim values return to normal at higher engine RPMs. This symptom often points to a loose or damaged intake manifold gasket, especially in older 2004 Tahoe models with high mileage.

Anonymous 2018-05-07 08:56

Thanks for the input! I'm planning to replace the intake manifold gasket in the coming days. Any advice on which bolts and grommets are most reliable and affordable? GM lists a set at $88, but I'm looking for cost-effective alternatives without compromising quality or installation safety.

Anonymous 2018-05-07 09:09

Consider checking rockauto.com for compatible parts—many users have found good value options there for intake manifold gaskets and related components in 2004 Chevrolet Tahoes.