P0325 on a GMC: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

You can drive, but the engine runs with reduced timing protection and fuel economy may drop, so have the knock sensor checked soon.

What P0325 means on a GMC

On a GMC, P0325 means the knock sensor on bank 1 is not sending a proper signal to the engine computer. The sensor detects engine knock so the computer can retard timing; without it the engine can't protect itself from pinging.

Is P0325 common on GMCs?

P0325 is common on GMC trucks and SUVs with the V8 engines, especially Sierra and Yukon models, and it also shows up on Terrain and Acadia crossovers. On the V8s the knock sensors sit under the intake manifold and are known to fail, often alongside a code for the bank 2 sensor.

Commonly reported on: Sierra, Yukon, Terrain, Acadia.

Symptoms

Check engine light on
Reduced fuel economy
Engine pinging under load
Slight loss of power

Common causes

most common: Failed knock sensor
common: Chafed or damaged sensor wiring harness
common: Corroded or loose sensor connector
rare: Engine computer issue

How to fix it

Fix	DIY?	Typical cost
Replace the knock sensor	Mechanic	$250–600
Repair the wiring harness near the sensor	Mechanic	$100–350
Clean and reseat the sensor connector	Yes	$20–60

Frequently asked questions

Can I drive a GMC with a P0325 code?

Yes, in most cases. The engine still runs, but without knock protection it may ping under load, and fuel economy can drop, so get it checked soon.

What usually causes P0325 on a GMC?

A failed knock sensor, which is common on GMC V8 trucks and SUVs like the Sierra and Yukon. The sensors sit under the intake manifold and often fail with age.

How much does it cost to fix P0325 on a GMC?

Replacing a knock sensor typically runs $250–600 with parts and labor because the intake manifold has to come off. Wiring repairs are usually $100–350.