What it means
Knock sensor D signal below lower plausibility — short to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Knock sensor D senses combustion vibration and sends a signal to the engine control module for knock control. This code means the signal is below the module's lower limit, commonly because the signal circuit is shorted to ground or has a poor connection.
Common causes
Most likely first.
- Short to ground
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Check-engine light
- Reduced engine power or acceleration
- Engine knocking may be more noticeable
How to diagnose it
- Capture freeze-frame data and check live sensor D data to confirm the low reading and note whether it changes with engine speed or movement.
- Locate sensor D from the vehicle's service information and inspect its connector and harness for chafing, water ingress, pushed-back pins, or contact with ground.
- With the circuit checked according to the manufacturer's safety procedure, gently move the sensor D harness while monitoring the signal for a change that reveals an intermittent short.
- Test the sensor D signal wire for a short to ground and check connector pin fit and circuit continuity against the manufacturer's specification.
- If the wiring and sensor test correctly, check for related module communication faults and investigate gateway or CAN network issues.
Common fixes
- Dry, clean, and reconnect a sensor D connector with moisture or poor contact.
- Repair the sensor D signal wire where it is chafed or shorted to ground.
- Restore a backed-out or damaged connector pin.
- Replace knock sensor D if it fails the manufacturer's electrical tests.
- Repair a confirmed gateway or CAN network fault.
Can I keep driving?
Limit driving and avoid hard acceleration or heavy loads because the module may not be receiving a usable knock signal from sensor D. Stop if you hear persistent engine knocking or experience a pronounced loss of power.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.