P0330Knock/Combustion Vibration Sensor B Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- The knock sensor is a piezoelectric structure-borne sound sensor bolted to the engine block; the module evaluates its signal per cylinder and retards ignition when it detects knock. Sensor B is the second sensor – bank 2 on V engines, but on some four-cylinders also bank 1. With a fault the module retards ignition across the board as protection – noticeable loss of power and higher consumption. P0330 means the sensor circuit is open or the signal stays below the noise threshold. GM feeds a 20 kHz test signal into the circuit and detects an open circuit when it does not cancel out, setting the code in the first trip; Ford sees any open or short as a knock signal that is too small compared with the speed- and load-dependent noise level (at least 1,500 rpm, 35 % load, warm engine). Ford traced cases on the 3.5 EcoBoost to a chafed sensor connector; GM fixed false codes on the LT4 and 1.5 by reprogramming.
- What you may notice
- Check engine light on
- Loss of power, sluggish response from ignition retard
- Higher fuel consumption
- Likely causes
- LikelyWiring or connector chafed, broken or corroded (sensor often under the intake manifold)
- PossibleKnock sensor faulty (cracked piezo, moisture, heat damage)
- PossibleSensor loose or wrongly torqued
- RareEngine software or diagnostic calibration
- RareEngine module input stage
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.