2015 Chevy Silverado P0171 and P0174 Lean Both Banks - Hesitation on Acceleration

Question

Checking for some advice on my 5.3 Silverado. It has been idling a bit rough and if I stomp on the gas it hesitates before picking up speed. The Check Engine light came on yesterday and my basic scanner shows lean codes for both banks.

Marcus Bell · Accepted Answer

The issue was a cracked PCV breather tube (part #12674639) located at the rear of the driver side valve cover. I performed a smoke test and saw it leaking right at the quick-connect fitting. Replaced the tube for about $35 and cleared the codes; fuel trims returned to +/- 3% immediately. Make sure to check the rubber O-ring inside that connector as they dry out over time.

Lina Brooks · Answer

Since it is both banks, you should look for a vacuum leak after the MAF sensor. Check the intake bellows for cracks and listen for a whistling sound while the engine is running.

Ashley Park · Answer

Check your fuel trims at idle and then at 2500 RPM. If the trims improve at higher RPM, it is almost certainly a vacuum leak. If they get worse, you might have a failing fuel pump or a clogged filter.

Chris Donovan · Answer

Common issue on the EcoTec3 engines is the PCV tube or the intake manifold gaskets. Sometimes the brake booster hose can also crack near the check valve causing a massive air leak.

2015 Chevy Silverado P0171 and P0174 Lean Both Banks - Hesitation on Acceleration

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