P0324: Knock control system error

Knock control system error

Severity: Inspect soon

P0324 means the engine computer cannot confirm its knock detection is working properly. The engine usually runs, often with less power because the computer plays safe with spark timing, but real knocking that goes undetected can damage pistons. Get it inspected soon.

It gets more serious if:

Stop: You hear loud, persistent knocking, pinging or a metallic rattle from the engine, especially under load. Heavy detonation can damage pistons, rings and bearings, and GM found some engines setting P0324 had internal parts contacting the pistons. Stop driving hard, and have it checked before further driving.

Source: how we rate severity

P0324 in short

P0324 means the engine computer did not get the response it expected from its knock sensing system. Common causes are a knock sensor or its wiring, real engine knock or mechanical noise, and software on some GM models. Power may drop as the computer retards timing. Get it inspected soon, sooner if the engine knocks.

Knock sensors listen for the sharp vibration of fuel igniting too early. When they hear it, the engine computer retards spark timing to protect the engine.

P0324 is a system-level code: the computer is not satisfied that the knock system is working, rather than seeing one sensor circuit open or shorted. That can be a sensor or wiring problem, but it can also be real knock or a mechanical noise the computer cannot make sense of.

GM has bulletins where P0324 came from a mechanical rattle or from internal parts contacting the pistons, and others fixed by a software update. If knock sensor circuit codes such as P0325 or P0326 are stored too, fix those first.

Most likely causes

Cause 1: Failed knock sensor
Common general cause
Why it ranks here
A sensor that has cracked, lost its mounting torque or failed internally can no longer report knock reliably.
What would change this
Rises if the sensor is damaged, loose or contaminated, or its output fails a shop test.
How to test the knock sensor
Cause 2: Damaged knock sensor wiring or connector
Common general cause
Why it ranks here
Knock sensors often sit under the intake manifold, where wiring gets heat-damaged, rubbed or soaked, and their small signal is easily lost.
What would change this
Rises if the connector is corroded or loose, or the wiring is damaged; knock sensor circuit codes stored alongside point here.
How to test the knock sensor
Cause 3: Mechanical noise or internal engine fault picked up as knock (some GM models)
Supported by vehicle data
Why it ranks here
GM found piston oil squirters contacting the pistons on some 2014 Silverado and Sierra 1500 trucks with P0324, and a rattle or spark knock noise on some 2014-2015 Spark models.
What would change this
Rises with a rattle or knock you can hear, or high knock retard on a scan tool; applies first to the listed models.
Cause 4: Real detonation from low-octane fuel, carbon or a lean or hot engine
Possible — needs testing
Why it ranks here
Low-octane fuel, carbon buildup, a lean mixture or overheating can cause real knock that confuses the system, but this has to be confirmed by testing.
What would change this
Rises after a tank of lower-octane fuel than specified, or with lean or temperature codes stored too.
Cause 5: Engine computer software (some GM models)
Supported by vehicle data
Why it ranks here
GM addresses P0324 on the 2024 Trax, Trailblazer, Encore GX and Envista with an ECM reprogram.
What would change this
Rises if a bulletin covers your vehicle and the update has not been done.
How to test the engine control module (ecm / pcm)
Cause 6: Engine computer fault
Possible — needs testing
Why it ranks here
A failed knock processing circuit in the computer is possible but rare; rule out the sensor, wiring and noise first.
What would change this
Only rises once the sensor, wiring and engine noise have been ruled out.
How to test the engine control module (ecm / pcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Read all stored codes and check for bulletins or software updates for your vehicle.
Low riskTool: scan tool, service information
- IfKnock sensor circuit codes (P0325-P0334) are stored too
  It meansFix the circuit codes first.
  Points to: Damaged knock sensor wiring or connector
- IfA bulletin or update covers P0324 on your vehicle
  It meansHave the update done first.
  Points to: Engine computer software (some GM models)
- IfOnly P0324
  It meansListen for engine noise.
  Go to step 2
Step 2: Listen to the engine at idle and while accelerating gently: note any rattle, ping or knock and when it happens.
Low riskTool: your ears, a helper
- IfPinging under load, especially after a fill-up
  It meansReal detonation is likely; check fuel octane and for lean or temperature codes.
  Points to: Real detonation from low-octane fuel, carbon or a lean or hot engine
- IfA rattle or knock at idle or light load
  It meansA mechanical noise may be confusing the knock system.
  Points to: Mechanical noise or internal engine fault picked up as knock (some GM models)
- IfNo unusual noise
  It meansInspect the sensor and wiring.
  Go to step 3
Step 3: With the engine off and cool, inspect the knock sensor connector and wiring you can reach for corrosion, looseness, heat damage or rubbing.
Low riskTool: flashlight, service information
- IfDamaged, loose or corroded wiring or connector
  It meansRepair the circuit, clear the code and retest.
  Points to: Damaged knock sensor wiring or connector
- IfWiring looks good
  It meansA shop should check the system.
  Go to step 4
Step 4: Have a shop watch knock retard on a scan tool during a controlled test (GM's Spark procedure uses repeated 1,800-2,000 rpm runs after a cold soak) and test the sensor output and mounting torque.
Best left to a shopTool: scan tool, service information, torque wrench
Warning:Load testing on the road or a dynamometer and internal engine inspection need shop equipment.
- IfKnock retard stays high with an audible noise
  It meansMechanical noise or real detonation; the engine needs further inspection.
  Points to: Mechanical noise or internal engine fault picked up as knock (some GM models)
- IfSensor output is weak or the sensor is loose
  It meansRe-torque or replace the sensor.
  Points to: Failed knock sensor
- IfSensor, wiring and engine test normal
  It meansThe engine computer is suspect.
  Points to: Engine computer fault

Symptoms

Reduced power or hesitation
Worse fuel economy
Pinging, knocking or rattling from the engine Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

Step 1: Write down every stored code and the freeze-frame data before clearing anything.
Step 2: Use the fuel octane your owner's manual specifies until the code is diagnosed.
Step 3: If a knock sensor is replaced, tighten it to the specified torque; a sensor that is too loose or too tight does not read correctly.
Warning:Many knock sensors sit under the intake manifold; removal may require draining coolant or removing parts. Follow the service information.

Parts and cost context

Knock sensor:Rule out wiring, engine noise and software updates before replacing the sensor; P0324 is a system code, not proof the sensor failed.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

2014 · Silverado 1500
Supported by vehicle data
GM links P0324 on some 2014 trucks to piston oil squirters contacting the pistons (PIP5149). This is an internal engine fault; have a dealer check it.
2014–2015 · Spark
Supported by vehicle data
GM has a diagnostic procedure for P0324 with a rattle or spark knock noise (PIP5251).
2024 · Trax
Supported by vehicle data
GM fixes P0324 and/or P0116 with an ECM reprogram (24-NA-064). Ask a dealer before replacing parts.
2024 · Trailblazer
Supported by vehicle data
GM fixes P0324 and/or P0116 with an ECM reprogram (24-NA-064).

PIP5149Status unverified
GM PIP5149: P0324, inspect oil squirters for piston contact
2014silverado-1500 · issued August 22, 2013 · NHTSA 10113207
On 2014 Silverado and Sierra 1500 with a MIL and P0324, remove the oil pan and inspect the piston oil squirters for contact; if contact is found the dealer calls GM about a replacement engine.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP5251Status unverified
GM PIP5251: P0324 and rattle or spark knock noise
2014–2015spark · issued December 23, 2014 · NHTSA 10114810
On the 2014-2015 Spark with P0324, possibly with a rattle or spark knock noise, cold soak the car and watch Total Knock Retard during repeated 1,800-2,000 rpm runs; readings above 6 degrees for more than 5 seconds call for further action.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
24-NA-064Status unverified
GM 24-NA-064: ECM reprogramming for P0324 and/or P0116
2024trax, trailblazer · issued April 2, 2024 · NHTSA 10252991
Reprogram the ECM to correct a MIL with P0324 and/or P0116 on the 2024 Trax, Trailblazer, Encore GX and Envista.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP5529Status unverified
GM PIP5529: additional diagnosis for P0324, P0326 and related codes
2013–2017camaro, malibu, impala, colorado · issued October 20, 2017 · NHTSA 10123274
Additional diagnosis for a MIL with combinations of P0324, P0326, P0331 and air, fuel and oxygen sensor codes on several 2013-2017 GM models. NHTSA's summary does not give the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

All Ignition and engine position sensors codes

Sources and review

P0324 Code: Knock Control System Error — CarParts.com Research Team
What Causes a Knock Sensor Code? 11 Common Causes — Rick's Free Auto Repair Advice (Rick Muscoplat) , July 27, 2022
GM PIP5251: P0324 and rattle or spark knock noise, 2014-2015 Spark — General Motors / NHTSA , December 23, 2014
GM PIP5149: P0324, inspect oil squirters for piston contact, 2014 Silverado/Sierra 1500 — General Motors / NHTSA , August 22, 2013
How to diagnose a faulty knock sensor — Delphi Technologies Aftermarket
GM 24-NA-064: ECM reprogramming for MIL with P0324 and/or P0116, 2024 Trax, Trailblazer, Envista, Encore GX — General Motors / NHTSA , April 2, 2024
GM PIP5529: additional diagnosis for P0324, P0326 and related codes, 2013-2017 GM — General Motors / NHTSA , October 20, 2017

Last reviewed: October 15, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Inspect soon

Most likely causes

Cause 1: Failed knock sensor

Cause 2: Damaged knock sensor wiring or connector

Cause 3: Mechanical noise or internal engine fault picked up as knock (some GM models)

Cause 4: Real detonation from low-octane fuel, carbon or a lean or hot engine

Cause 5: Engine computer software (some GM models)

Cause 6: Engine computer fault

What to test first

Step 1: Read all stored codes and check for bulletins or software updates for your vehicle.

Step 2: Listen to the engine at idle and while accelerating gently: note any rattle, ping or knock and when it happens.

Step 3: With the engine off and cool, inspect the knock sensor connector and wiring you can reach for corrosion, looseness, heat damage or rubbing.

Step 4: Have a shop watch knock retard on a scan tool during a controlled test (GM's Spark procedure uses repeated 1,800-2,000 rpm runs after a cold soak) and test the sensor output and mounting torque.