P0174 on a GMC: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Drivable short-term, but a lean condition on bank 2 should be diagnosed soon to avoid drivability issues.

What P0174 means on a GMC

On a GMC, P0174 means the engine is running lean on bank 2 — the side opposite cylinder 1 — because too much air or too little fuel is getting in. The computer has added as much fuel as it can and still can't balance the mixture. It's the bank 2 version of P0171.

Is P0174 common on GMCs?

P0174 shows up on GMC V6 and V8 models like the Sierra, Yukon, and Acadia. Intake manifold gasket leaks are a well-known cause of lean codes on GM engines, especially the 5.3L and 6.0L V8s used in GMC trucks. Vacuum lines and dirty MAF sensors are also common culprits on higher-mileage GMCs.

Commonly reported on: Sierra, Yukon, Acadia.

Symptoms

Check engine light is on
Rough or surging idle
Hesitation or lack of power
Poor fuel economy

Common causes

most common: Intake manifold gasket leak
common: Vacuum leak (cracked hose or fitting)
common: Dirty or failing mass air flow (MAF) sensor
less common: Faulty upstream oxygen sensor (bank 2)
less common: Weak fuel pump or clogged fuel filter

How to fix it

Fix	DIY?	Typical cost
Inspect and repair vacuum leaks (hoses, fittings)	Yes	$10–100
Clean the mass air flow sensor with MAF cleaner spray	Yes	$10–20
Replace a leaking intake manifold gasket	Mechanic	$150–400
Replace the bank 2 upstream oxygen sensor if it's reading wrong	Yes	$60–200

Frequently asked questions

Why is P0174 common on GMC V8 engines?

The intake manifold gaskets on GM V8s can leak air as they age, letting unmetered air into bank 2. That's one of the most common ways a GMC sets P0174.

What does bank 2 mean on a GMC?

Bank 2 is the side of the engine that does not contain cylinder 1. Only V6 and V8 GMCs have a bank 2, so 4-cylinder models won't set P0174.

Can I keep driving my GMC with P0174?

Short trips are fine, but a lean condition can cause rough idle and hesitation over time. Have it diagnosed soon so a small leak doesn't turn into a bigger repair.