Did E85 Fuel Damage this Engine? Impala 3.6 P0171 P0174

Dealing with persistent P0171 P0174 codes on a 2019 Chevrolet Impala. Watch us tackle this difficult engine repair job.

This 2019 Chevrolet Impala arrived at the shop with a 3.6 liter V6 that simply refuses to run properly. We have already exhausted several common fixes, including replacing sensors, swapping the throttle body, and hunting for vacuum leaks, yet the engine continues to struggle.

When standard parts replacement fails, methodical automotive diagnostics become the only way to isolate the root cause. We walk through the frustration of troubleshooting a vehicle that defies easy solutions and show the reality of complex engine repair work.

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0:00 The Mystery of the Rough Running Impala

1:21 Taking Serious Action Under the Hood

2:58 Analyzing the Flex Fuel Diagnostic Strategy

5:27 Investigating the High Pressure Fuel System