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Dave Nova
Dave Nova, Buick Technician
Category: Buick
Satisfied Customers: 1808
Experience:  ASE Master Certification. GM World Class Certification
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2000 LeSabre Limited 3.8 V-6. Code P0171 only when air conditioner

Customer Question

2000 LeSabre Limited 3.8 V-6. Code P0171 only when air conditioner is running never when it's off. Replaced MAF unit, both O2 sensors, air filter and had ejectors cleaned; coolant is full. Local mechanic says no problem except "EGR was slow" (??)!
Submitted: 2 years ago.
Category: Buick
Expert:  Gary replied 2 years ago.
Hi there,P0171 is a lean DTC for Bank 1.So I would agree with a dirty injector, but why did he replace the MAF, BOTH O2 sensors and the air filter?If the car performs normally everywhere, but still logs a P0171, then it could be a vacuum leak on Bank 1 (not common), or carbon buildup on the back of the intake valves.Bank 1 must be just slightly unlucky to be logging this code. Bank 2 is probably not far behind, just not enough to log P0174.Subaru Upper cylinder clean, or any combustion chamber cleaning product is worth a go.I have done it many many times to fix problem cars.Carbon buildup is bad in any engine, the main reason why Subaru has their own product, and why they sell it on every service.It is VERY good at keeping the engine clean.Can you suggest this to your local mechanic?Hope this helps.Gary