What it means
The ECM detects a low 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 sends an A/C compressor motor voltage signal to the control module. P0EAC sets when that signal is lower than the module's permitted range, commonly because the signal is pulled toward ground, the sensor is internally shorted, or a connection has excessive resistance.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- 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
- Capture freeze-frame and live sensor B data with related A/C codes to confirm the low reading and note whether it changes with compressor operation.
- Inspect the sensor B connector and harness for corrosion, moisture, crushed insulation, or a signal wire contacting ground.
- Check the sensor B ground and reference connections for corrosion or excessive resistance using manufacturer wiring information.
- With the system disabled as specified by the manufacturer, test the signal wire for a short to ground and check circuit continuity.
- If wiring and terminal checks pass, test voltage sensor B against the manufacturer's specification to identify an internal short.
Common fixes
- Clean or repair corroded sensor B connector terminals.
- Repair the signal wire where it is shorted to ground or damaged.
- Restore a sound ground or reference connection to voltage sensor B.
- Replace voltage sensor B if it fails its specified circuit test.
Can I keep driving?
The A/C may be disabled or cool intermittently, and a hybrid warning may appear. Driving may be possible if the vehicle shows no stop-driving warning, but avoid relying on cabin climate control and get the circuit checked promptly.
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.