What it means
CAC bypass position sensor A reading implausible. 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
Charge air cooler bypass position sensor A provides feedback about the bypass valve’s position. The module checks whether that reading is plausible and sets P024D when it is outside the expected range or does not behave consistently with valve movement; this points to a performance or plausibility issue rather than a specific low or high signal.
Common causes
Most likely first.
- Sensor reading drifted
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- Check-engine light on
- Reduced engine power or acceleration
- Poor turbo response
- Reduced fuel economy
How to diagnose it
- Read freeze-frame data and compare sensor A position feedback with commanded bypass position, if available.
- Inspect sensor A mounting for looseness and check its connector and harness for chafing, water entry, or backed-out pins.
- Move the bypass valve through its range, if supported, while watching sensor A data for smooth, plausible changes.
- Wiggle the harness while monitoring the reading to look for an intermittent connection or signal disturbance.
- Test sensor A and its circuit against the manufacturer’s specification before replacing the sensor.
Common fixes
- Secure sensor A if its mounting is loose and verify that the valve moves freely.
- Repair chafed wiring, water-damaged connector seals, or pushed-back terminals in the sensor A circuit.
- Replace position sensor A if its reading remains out of range after wiring and mounting checks.
- Correct a binding bypass valve if it causes sensor feedback to disagree with movement.
Can I keep driving?
Drive gently and avoid hard acceleration or towing because bypass response and engine power may be reduced. Stop if the vehicle’s power drops enough to make driving unsafe.
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.