P0DF9: Generator Inverter Temperature Sensor C Circuit High

What it means

The ECM detects a high fault on the generator inverter temperature sensor c 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

Generator inverter temperature sensor C reports temperature to the control module through its signal circuit. This code sets when the signal is above the expected electrical range, which can result from a short to battery voltage, an open sensor, or a poor connector connection.

Common causes

Most likely first.

1. Signal wire shorted to B+
2. Open sensor
3. Connector pins corroded - high contact resistance

Symptoms

• Hybrid/EV system warning light on
• Power may be reduced if the inverter temperature cannot be monitored reliably

How to diagnose it

1. Record freeze-frame data and compare sensor C’s live reading with sensors A and B for a fixed or implausibly high value.
2. With the hybrid system powered down per service information, inspect sensor C’s connector for corrosion, loose pins, or damage.
3. Check the sensor C signal wire for a short to a battery-positive feed or damaged insulation.
4. Test for an open circuit and verify terminal contact using the manufacturer’s procedure.
5. Test sensor C against the manufacturer’s specification to check for an internal open.

Common fixes

• Repair loose, damaged, or corroded sensor C connector terminals.
• Repair the signal wire if it is shorted to battery voltage or damaged.
• Replace sensor C if it is open internally or fails the specified test.
• Repair any confirmed open or connection fault between sensor C and the control module.

Can I keep driving?

Limit driving and avoid heavy loads because unreliable inverter temperature feedback may cause reduced hybrid power. Stop safely if overheating signs or a substantial power loss occur.