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Customer Concern: Malfunction Indicator Lamp (MIL) on. Powertrain Control Module (PCM) DTC P0171.

Average Reported Mileage: 100343

P0171 p0174 System Lean Trailblazer “Fixed with no parts”

Mass air flow sensor cleaner: https://amzn.to/2HbyNJm

Air filter and tune up kit for Chevy Trailblazer: https://amzn.to/2vt1pbA

Tests/Procedures: 1. Check for a vacuum leak by spraying water around the engine and see if it reacts.

2. At the Mass Air Flow (MAF) sensor connector locate, backprobe and ground the Yellow wire. Reset fuel trims using the scanner and see if Long Term Fuel Trim (LTFT) stay in single digits.

3. Access the fuel system test port, near the fuel tank and fuel filter.

4. Connect a pressure gauge to the port.

5. Fuel pressure should be steady at all loads, 50-57 PSI.

6. Verify that the fuel pressure value is between the range of 50-57 and not dropping under load.

7. Check fuel filter for restriction.

8. Clean the throttle body assembly.

9. Run cleaner through the injectors.

Vehicle Application:

2006 Rainier 4.2

2006 Trailblazer 4.2

2006 Trailblazer EXT 4.2

2006 Envoy 4.2

2006 Envoy XL 4.2

2006 Ascender 4.2

2006 9-7x 4.2

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