Code
P0AF6
Generic
P — Powertrain
Drive Motor Inverter Temperature Sensor B Circuit Intermittent/Erratic
Views:
UK: 17
EN: 19
RU: 13
AI status
Completed
Completed
100%
Causes
- Intermittent open or short in the sensor signal or reference wiring
- Corroded, loose or damaged connector at the sensor or inverter
- Faulty temperature sensor (thermistor) in the inverter assembly
- Poor ground or supply reference to inverter/VCU
- Water ingress, contamination, or physical damage to harness/connectors
- Intermittent internal inverter/VCU electronics fault
Symptoms
- MIL / hybrid/inverter warning lamp illuminated
- Logged intermittent fault codes, possibly recurring after clearing
- Possible reduction of drive power or entry into limp/protective mode
- Inconsistent or erratic inverter temperature values displayed in live data
- Noisy or unstable vehicle electrical behavior under certain conditions
What to check
- Read freeze frame and full fault history with a capable scan tool; note conditions when code set
- Inspect sensor connector(s) and wiring for corrosion, damage, or water ingress
- Check for TSBs, software updates, and manufacturer-specific guidance for inverter faults
- Monitor live data for inverter temperature B while operating and while moving/rocking harness
- Perform a wiggle test on the wiring while observing live data for intermittent jumps
- Backprobe connector and measure reference voltage, signal voltage, and ground continuity
Signal parameters
- Sensor type: typically an NTC thermistor inside the inverter (resistance decreases as temperature rises)
- Typical signal: a low-voltage sensor circuit referenced to inverter/VCU (often 0–5 V signal to control module)
- Room temperature resistance: typically in the kΩ range (design dependent) — consult vehicle-specific specs
- Expected behavior: smooth, monotonic change in resistance/voltage with temperature; intermittent spikes or open-circuit indicate fault
- For bench tests: measure resistance of sensor as it is warmed/cooled and confirm consistent response
Diagnostic algorithm
- Retrieve freeze frame and code history; note vehicle state (temperature, load, speed) when fault occurred.
- Inspect visible wiring and connector at inverter for damage, corrosion, signs of water, or loose pins.
- With ignition on (engine off, high-voltage system safe per manufacturer procedures), backprobe the sensor connector and verify reference voltage and ground integrity.
- Monitor live inverter temperature B signal with scan tool while wiggling harness and turning steering/wheels or raising/lowering vehicle to reproduce intermittent behavior.
- Measure sensor resistance at the connector and compare to specification or to sensor A. Heat/cool the sensor (carefully) to confirm consistent resistance change.
- Perform continuity and insulation resistance checks on the sensor wiring between the inverter connector and the control module ground/power points.
- Repair any damaged wiring, clean/replace corroded connectors, and secure harness routing to prevent chafing. Re-test for recurrence.
- If wiring and connector are good but sensor output remains erratic, replace the inverter temperature sensor or inverter assembly per service procedures.
- If sensor replacement does not correct the issue, consider inverter/VCU internal fault — consult manufacturer procedures; replacement or module rework may be required.
- Clear codes and perform a road/test cycle to verify the fault does not return; document repair and test data.
Likely causes
- Damaged/loose connector or pin corrosion at the inverter temperature sensor
- Broken or chafed wiring causing intermittent contact when harness moves
- Failed temperature sensor (open/partial short or drifting resistance)
- Poor ground or reference voltage to the inverter/VCU
- Intermittent internal fault inside the inverter (less common)
Fault status
Status
Drive Motor Inverter Temperature Sensor B Circuit Intermittent/Erratic
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
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