What it means
The ECM detects a circuit high fault on the drive motor inverter temperature sensor d 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
Inverter temperature sensor D reports the temperature at its monitored point in the drive motor inverter to the ECM. P0BD9 sets when the D signal circuit voltage rises above its acceptable range, commonly from a signal short to battery voltage or an open sensor circuit; the ECM then cannot trust that reading.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Read freeze-frame and hybrid control data to see when sensor D went high and whether other inverter temperature readings remain plausible.
- With the vehicle powered down according to the manufacturer's procedure, inspect sensor D's connector and harness for an open, corrosion, or damaged insulation that could contact a power feed.
- Test the D signal wire for a short to B+ and check circuit continuity and connector contact condition using the manufacturer's procedure.
- Compare sensor D's live value with other inverter temperature readings as operating conditions change; a fixed extreme reading can help distinguish an open or short from a real temperature change.
- If the harness checks pass, test sensor D against the manufacturer's specification before investigating the control module.
Common fixes
- Reseat the sensor D connector and clean or repair corroded terminals.
- Repair an open in the sensor D signal or connector circuit.
- Repair insulation damage causing the signal wire to contact B+.
- Replace sensor D if it fails the manufacturer's test.
Can I keep driving?
Keep driving only as far as needed to reach a safe place if the vehicle still responds normally; reduced motor power or shutdown may occur without dependable inverter temperature data. Avoid heavy loads and stop safely if a hybrid warning or limp mode appears.
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.