Cause
Faulty inverter coolant temperature sensor
The sensor measuring the temperature of the coolant serving the power electronics has failed or drifted.
What makes this worth more than an ordinary sensor fault is how much rests on the number. The reading governs two limits at once: how much torque the car will deliver, and how fast it will let itself charge. Both are set by what the inverter, the on-board charger and the DC/DC converter can safely tolerate, and all three are judged from this circuit.
So a sensor reading falsely high makes a perfectly healthy car derate and charge slowly, and there is nothing else visibly wrong to explain it. That is the case that gets chased through expensive components. Reading falsely low is rarer and worse, because the protection that should intervene never does.
The most useful clue is that it should not be alone. Power electronics on a shared coolant loop cannot be at wildly different temperatures, so comparing this reading against the other sensors in the same circuit — the inverter's own, the converter's — settles it quickly. One sensor disagreeing with its neighbours is the sensor. All of them rising together is the cooling.
And the cheap thing first: the electronics coolant circuit is a separate reservoir from the engine's on most vehicles, easy to overlook at service, and awkward to bleed — so low coolant and trapped air both produce readings that look like a failed sensor.
Typically a moderate job.
Codes this can cause (27)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0A00 Motor Electronics Coolant Temperature Sensor A Circuit Likely for this code High
- P0A01 Motor Electronics Coolant Temperature Sensor A Circuit Range/Performance Likely for this code High
- P0A02 Motor Electronics Coolant Temperature Sensor A Circuit Low Likely for this code High
- P0A03 Motor Electronics Coolant Temperature Sensor A Circuit High Likely for this code High
- P0A04 Motor Electronics Coolant Temperature Sensor A Circuit Intermittent Likely for this code High
- P0CBC Drive Motor A Coolant Temperature Sensor Circuit Likely for this code High
- P0CBD Drive Motor A Coolant Temperature Sensor Circuit Range/Performance Likely for this code High
- P0CBE Drive Motor A Coolant Temperature Sensor Circuit Low Likely for this code High
- P0CBF Drive Motor A Coolant Temperature Sensor Circuit High Likely for this code High
- P0CC0 Drive Motor A Coolant Temperature Sensor Circuit Intermittent Likely for this code High
- P0CEE Hybrid/EV Electronics Coolant Temperature Sensor A Circuit Likely for this code High
- P0CEF Hybrid/EV Electronics Coolant Temperature Sensor A Circuit Range/Performance Likely for this code High
- P0CF0 Hybrid/EV Electronics Coolant Temperature Sensor A Circuit Low Likely for this code High
- P0CF1 Hybrid/EV Electronics Coolant Temperature Sensor A Circuit High Likely for this code High
- P0CF2 Hybrid/EV Electronics Coolant Temperature Sensor A Circuit Intermittent/Erratic Likely for this code High
- P0E81 Auxiliary Cooling System Coolant Temperature Sensor A Circuit Likely for this code High
- P0E82 Auxiliary Cooling System Coolant Temperature Sensor A Circuit Range/Performance Likely for this code High
- P0E83 Auxiliary Cooling System Coolant Temperature Sensor A Circuit Low Likely for this code High
- P0E84 Auxiliary Cooling System Coolant Temperature Sensor A Circuit High Likely for this code High
- P2B20 Hybrid/EV Electronics Coolant Temperature Sensor B Circuit Likely for this code Moderate
- P2B21 Hybrid/EV Electronics Coolant Temperature Sensor B Circuit Range/Performance Likely for this code Moderate
- P2B22 Hybrid/EV Electronics Coolant Temperature Sensor B Circuit Low Likely for this code Moderate
- P2B23 Hybrid/EV Electronics Coolant Temperature Sensor B Circuit High Likely for this code Moderate
- P2B24 Hybrid/EV Electronics Coolant Temperature Sensor C Circuit Likely for this code Moderate
- P2B25 Hybrid/EV Electronics Coolant Temperature Sensor C Circuit Range/Performance Likely for this code Moderate
Information, not instruction
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