P032D: Knock/Combustion Vibration Sensor C Circuit High
What to do
The car will feel slightly flat rather than broken. With no trustworthy knock sensor the engine backs its ignition timing off as a precaution, which costs a little performance and economy.
Say whether you can hear any pinking or rattling under load — a metallic tinkling when accelerating hard or going up a hill. That is the one answer that makes this urgent rather than routine, because it means the sensor may be reporting real knocking.
Mention any recent ignition work — coils, leads, plugs — or any wiring repair near the engine. This sensor's cable is screened because it carries a tiny signal through a very electrically noisy place, and a screen that has lost its earth, or a lead re-routed against an ignition cable, produces exactly this fault.
Ask for the wiring and its screening to be checked before the sensor is replaced, since a high reading points at the harness more often than at the sensor.
What this code means
The third knock sensor's signal is above the range the circuit should be able to produce. The sensor's job is at P0325 and what a C sensor implies about the engine is at P032A.
High on a knock sensor is a different kind of statement from high on most sensors, and the reason is worth understanding. A knock sensor is not powered. It is a piezoelectric element: squeezing it generates its own small voltage, so there is no reference supply to short to and no pull-up to fail high. What the module actually sees is the element's own output against a bias voltage it applies to the line, and a reading above the valid range means that line has picked up something it should not have.
Which makes the causes unusually specific:
- A short to a supply voltage in the harness, which is the textbook answer and the least common in practice.
- Ignition interference. These are low-level signals in the noisiest place on the vehicle, and their cable is screened for that reason. A screen that has lost its earth, or a lead routed against an ignition cable after a repair, injects exactly this fault — and it comes and goes with engine speed, which is the giveaway.
- A sensor that is over-tightened, preloaded so hard that ordinary vibration produces an output far larger than the calibration expects.
- Genuine severe knocking, which is rare as an explanation and serious if it is the right one — worth ruling out first by asking whether the engine pinks under load.
Note that this code and its low sibling are usually diagnosed together and are not equally informative. A low reading points at an open circuit or a dead element; a high one points at the harness and its screening, which is why the routing of the cable matters more here than the sensor does.
Likely causes
Start here
- Wiring shorted to voltage · moderate
- Intermittent wiring fault · moderate
- Faulty knock sensor · moderate
Less common
- Incorrect knock sensor mounting torque · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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