P0328
Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor)
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The P0328 code indicates that Knock Sensor 1 on Bank 1 is sending a voltage signal that exceeds the ECM's maximum expected threshold. This is a more concerning code than P0327 (low input) because a high reading could mean the engine is actually experiencing significant detonation — a condition that can cause serious engine damage if ignored.
Before assuming the sensor is faulty, it's important to determine whether the engine is actually knocking. Common causes of real detonation include carbon buildup on the pistons and cylinder heads, using fuel with a lower octane rating than recommended, a lean fuel condition, or engine overheating. If the engine is genuinely knocking, replacing the sensor won't fix the problem and the underlying cause needs to be addressed.
This code warrants more urgency than other knock sensor codes. If the engine is truly detonating and the ECM can't properly manage timing because it thinks the signal is a sensor fault, you risk piston and bearing damage. Have this diagnosed within the week, and avoid heavy acceleration or towing until the cause is confirmed. If it turns out to be a sensor or wiring issue, the repair is straightforward and affordable.
Severity
Symptoms
- •Check Engine light is on
- •Noticeable loss of engine power
- •Engine pinging or knocking sounds under acceleration
- •Poor fuel economy
- •Rough running or misfiring sensation
Likely Causes
The engine is experiencing real detonation due to carbon buildup, overheating, low-octane fuel, or a lean fuel condition, producing legitimately high knock sensor readings.
The knock sensor has failed in a way that produces an abnormally high voltage output regardless of actual engine vibration levels.
A short circuit in the knock sensor wiring harness is introducing external voltage into the circuit, causing artificially high readings.
Worn rod bearings, piston slap, or other internal engine problems are creating excessive vibration that the knock sensor correctly reports as high.
The engine control module may have an internal fault causing it to misread the knock sensor signal as high input.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Diagnose and address any actual engine knock (carbon cleaning, fuel system service)
- Replace the knock sensor
- Repair shorted wiring in the knock sensor circuit
- Use manufacturer-recommended octane fuel
- Inspect for engine mechanical issues
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Videos
How to Fix P0328 Engine Code in 2 Minutes
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Causes and fixes Code p0328 : knock sensor voltage high issues
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