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2005 Dodge Ram 5.7L Hemi Engine P0171 and P0174 Codes: Diagnosis and Fixes After MAF Cleaning

Model: 2005 Ram 5.7 Hemi Fault Code: P0171 Posted: 2007-04-24 13:40

I recently encountered P0171 (Fuel Trim System Lean - Bank 1) and P0174 (Fuel Trim Too Lean - Bank 2) on my 2005 Dodge Ram 5.7L Hemi. I cleaned the MAF sensor, and for a few days, the truck ran smoothly. However, it has started surging again, with black exhaust smoke and soot buildup on the bumper. Fuel efficiency has dropped from 15 to 10 MPG. Notably, no diagnostic codes are currently stored in the ECU. I've checked for vacuum leaks but found none. Are there specific areas I should inspect? What other potential causes could be responsible? I suspect issues with fuel delivery or sensor accuracy, especially since the MAF was cleaned and initially resolved the problem—yet symptoms have returned. Without a live data scan, it's difficult to pinpoint the root cause.

Related fault codes
P0171P0174
Comments (5)
Anonymous 2007-04-24 14:57

P0171 and P0174 indicate a lean fuel/air mixture (excess air, insufficient fuel) across both engine banks. While vacuum leaks are common culprits, ensure all vacuum hoses are intact—check for cracks, holes, or loose connections. Also inspect the intake manifold for any gaps or breaches. Other potential causes include low fuel pressure from a failing fuel pump, clogged fuel injectors, or malfunctioning sensors such as the IAT (Intake Air Temperature) or MAF (Mass Air Flow). Since you cleaned the MAF and saw temporary improvement, it's possible the sensor is still faulty or improperly calibrated. A live scan of engine data would provide more accurate diagnostics.

Anonymous 2007-04-24 15:29

Important correction: The 2005 Dodge Ram 5.7L Hemi does not have a traditional MAF sensor—instead, it uses an Electronic Throttle Body (ETB). You may have mistakenly cleaned the wrong component. If you attempted to clean or modify the ETB, that could have caused damage and led to current symptoms. This system is highly sensitive. DIY repairs without proper tools and knowledge can result in serious issues. If your vehicle still has factory warranty (common until 2012), it's best to consult a dealer for diagnosis and repair. Many of these codes are addressed via software updates, which were available for this model year. Also consider EGR valve problems—clogged or malfunctioning EGR systems can trigger P0171/P0174 due to improper exhaust gas recirculation.

Anonymous 2007-04-24 16:13

Agreed. The 2005 Ram is relatively new and likely still under warranty for key components. For vehicles manufactured through 2012, factory warranties typically cover major engine systems for up to 7 years or 70,000 miles. It's strongly recommended to avoid DIY modifications on complex systems like the throttle body or EGR. Letting a certified dealer handle repairs ensures safety and preserves warranty coverage.

Anonymous 2007-04-24 17:26

I took my truck to the dealer, where they performed exhaust work and installed an aftermarket air intake. Unfortunately, this combo severely disrupted sensor readings. After replacing both the O2 sensors and the IAT sensor (not the MAF), performance improved significantly. This experience highlights how aftermarket modifications can interfere with emissions and sensor calibration.

Anonymous 2007-04-25 07:21

Removing the aftermarket air intake is critical—such modifications often disrupt airflow sensing, leading to incorrect fuel trim readings and triggering lean codes. These installations may void your warranty, especially if not approved by the manufacturer. I’ve seen multiple cases where improperly installed intakes caused ETC (Electronic Throttle Control) malfunctions or sensor errors. Your dealer likely advised similar solutions. Always verify compatibility with OEM systems before installing aftermarket parts.