What it means
The active engine mount B control circuit reports a control circuit high condition. Vibration damping cannot be modulated.
At a glance
- Usually lights the check-engine light
How it works
Active engine mount B uses an electrical actuator so the control module can adjust how it dampens engine movement. P0AB8 sets when the module sees mount B's control circuit above its expected range, which can result from a wire shorted to battery voltage, an open actuator, or a high-resistance connector.
Common causes
Most likely first.
- Control wire shorted to B+
- Open actuator
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light may illuminate
- Increased engine vibration, especially at idle
- Clunk or thump when starting, stopping, or shifting
How to diagnose it
- Record freeze-frame data and check whether the fault returns at idle or during starting, stopping, or shifting.
- Inspect mount B's connector for corrosion, loose fit, or damaged terminals, and follow the harness for chafing or contact with a powered wire.
- Use the vehicle wiring diagram to check the mount B control wire for a short to battery voltage.
- Check continuity through the mount B actuator and circuit for an open, comparing results with the manufacturer's specification.
- If the wiring and connector are sound, test the actuator and module output using the specified procedure.
Common fixes
- Clean and secure corroded mount B connector terminals if serviceable.
- Repair a control wire shorted to battery voltage.
- Replace damaged connector terminals or wiring.
- Replace the mount B actuator if it is open or fails its specified test.
Can I keep driving?
If vibration and clunking are mild, drive gently only as needed to reach a repair location; avoid abrupt shifts and hard acceleration. Stop if engine movement or impacts become severe because they can strain nearby components.
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.