P017C: How to Diagnose & Fix — Cylinder Head Temperature Sensor Circuit Low
2 vehicles · 1 makes
How to diagnose and fix P017C: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Audi RS Q8 · 2020–2021
Audi TSB 2062951/4 covers all 2020 RS Q8 vehicles and early-production 2021 vehicles built before chassis WUARRDF11MD011353 (the first vehicle with the improved part) when a red coolant warning appears and the engine controller stores P218100, P017B00, P017C00 or P017E00. Audi documents that a damaged or pinched O-ring can allow moisture to reach coolant temperature sender G407. The fault is in this sensor, not in the turbo coolant hoses or pump.
Common Symptoms
- Red coolant warning lamp
How to Fix
Have the vehicle checked with Audi Guided Fault Finding and inspect G407 and its O-ring. Replace G407 only if the O-ring is damaged or pinched and the diagnosis matches the bulletin; follow the related Audi diagnostic path if additional listed faults are stored. Do not replace turbo coolant hoses, pumps or other cooling parts based on this warning alone.
Sources for this issue (1)
Audi SQ8 · 2020–2021
Audi TSB 2062951/4 covers all 2020 SQ8 vehicles and early-production 2021 vehicles built before chassis WA1CWBF17MD010458 (the first vehicle with the improved part) when a red coolant warning appears and the engine controller stores P218100, P017B00, P017C00 or P017E00. Audi documents that a damaged or pinched O-ring can allow moisture to reach coolant temperature sender G407. This is a sensor fault, not a sign of a failing hose or pump.
Common Symptoms
- Red coolant warning lamp
How to Fix
Have the vehicle checked with Audi Guided Fault Finding and inspect G407 and its O-ring. Replace G407 only if the O-ring is damaged or pinched and the diagnosis matches the bulletin; follow the related Audi diagnostic path if additional listed faults are stored. Do not replace turbo coolant hoses, pumps or other cooling parts from this card alone.
Sources for this issue (1)
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P017C code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P017C mean?
P017C stands for "Cylinder Head Temperature Sensor Circuit Low." The engine control module sees the cylinder head temperature sensor signal pulled to ground - a short-to-ground condition on the sensor circuit, which the ECM reads as an impossibly high temperature. On the Audi 4.0T V8 documented in TSB 2062951, this is typically caused by water intrusion past a damaged O-ring inside the plastic housing of coolant temperature sender G407, which bridges the sensing circuit.
What are the most common causes of P017C?
The most common causes of P017C are: Moisture inside the G407 coolant temperature sender housing from a damaged O-ring (Audi TSB 2062951), Chafed or pinched sensor wiring shorting to chassis ground, Coolant or water in the sensor connector, Internally shorted temperature sensor element. The specific cause varies by vehicle.
How much does it cost to fix P017C?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P017C?
Au7o has documented P017C across 2 vehicle models from 1 manufacturers: Audi.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.