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Dan, ASE Certified Technician
Category: Chevy
Satisfied Customers: 2270
Experience:  20 Year Factory Trained Current GM Technician
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i have a 2006 Chevy Trailblazer with 4.2 liter.SES light is

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i have a 2006 Chevy Trailblazer with 4.2 liter.SES light is on and code PO171 is present.Bank 1 Too lean.Is this a code for an 02 sensor lean? Was told these trucks have ECM updates that are required for lean conditions.Can you shed some light on this problem?
Submitted: 6 years ago.
Category: Chevy
Expert:  Dan replied 6 years ago.
Hello <a href=""Customer

By the time the 2006 models cane out, GM has fixed the problems with the oxygen sensor for this code. But they did install a MAF (mass Air FLow) sensor on it. If the MAF sensor reads incorrectly or has an air leak between the MAF sensor and the throttle body, it can cause a P0171 code to set. Sometimes the oil change places check the air filter and does not get the air tube back on right and Cause unmetered air to enter in the engine and cause problems. Check the air tubes first. The MAF sensor if mounted to the air tube by the air filter.
Also if the MAF sensor is reading incorrectly, it can cause this. You would need a scan tool to diagnose this.
ALso I seen people add the E85 gas in and cause it to run lean also.
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