P0A05 code meaning
Motor Electronics Coolant Pump A Control Circuit/Open
Powertrain system Generic code P0Axx codes Check engine light
What P0A05 means
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.
P0A05 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0A05
- 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
Common causes of P0A05
- Most 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
- Less likelyBlown pump fuse or missing supply, so the control input sees no load
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Motor electronics coolant pump aWiring harnessHybrid control module
What each part of P0A05 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| 05 | The exact fault in that area. |
What to do next
- Note P0A05 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0A05
What does P0A05 mean?
P0A05 means "Motor Electronics Coolant Pump A Control Circuit/Open". The electric pump that circulates coolant through the inverter, converter and drive motor loop is driven by a control line from the hybrid module. It is a generic code, so it means the same on every make.
Is it safe to drive with P0A05?
Drive gently and only to a workshop. With P0A05 the car can go into limp mode (reduced power) to protect itself.
Will P0A05 fail an emissions test?
Yes, it can. P0A05 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0A05 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P0A05 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.