P0A05Motor Electronics Coolant Pump A Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The electric pump that circulates coolant through the inverter, converter and drive motor loop is driven by a control line from the hybrid module. P0A05 means that line shows an open circuit or a fault the driver cannot classify further. No manufacturer documents P0A05 publicly. GM's Chevrolet Volt tables cover the same pump under P0CE9, set when the control line is open or shorted in 16 of 20 samples at 250 ms, Type B with MIL after two trips. CARB requires inverter cooling outputs to be checked, and Toyota patents describe how pump faults are told apart from other cooling faults. Low and high faults are P0A06 and P0A07; pump B is P0B38. Without circulation the electronics heat up quickly and power is cut.
- What you may notice
- Hybrid system warning or check engine light
- Electric drive power reduced, especially in warm weather or under load
- Follow-up inverter overtemperature codes such as P0A93
- Likely causes
- LikelyPump connector loose or corroded, often from road splash at the low-mounted pump
- PossibleBroken control wire between module and pump
- PossibleFailed electronics or open winding inside the pump
- RareBlown pump fuse or missing supply, so the control input sees no load
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.