What it means
The ECM detects a high fault on the a/c compressor motor voltage sensor b circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Voltage sensor B reports A/C compressor motor voltage to the control module. P0EAD sets when the sensor B signal rises above its permitted range, which can happen with a signal wire shorted to battery voltage, an open sensor, or a poor connector connection.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or hybrid system warning light
- Air conditioning may not cool
- Cooling may be intermittent
How to diagnose it
- Record freeze-frame and live sensor B data with related compressor codes to verify the high reading and its operating context.
- Inspect the sensor B connector and harness for a backed-out terminal, corrosion, damaged insulation, or contact with a power wire.
- Using the manufacturer's wiring information, check the sensor B reference and ground connections for opens or poor contact.
- With the system made safe according to manufacturer instructions, test the signal circuit for a short to battery voltage and for continuity.
- If the wiring and connector pass, test voltage sensor B against the manufacturer's specification for an open or failed sensor.
Common fixes
- Secure the sensor B connector and repair corroded or loose terminals.
- Repair the signal wire if it is shorted to battery voltage or damaged.
- Restore an open reference or ground connection.
- Replace voltage sensor B if it remains open or outside specification after circuit repairs.
Can I keep driving?
A/C cooling may be unavailable or intermittent, and a hybrid warning can accompany the fault. Follow any vehicle stop-driving warning; otherwise, avoid depending on the A/C and arrange diagnosis soon.
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.