P017B on Audi: How to Diagnose & Fix
Cylinder Head Temperature Sensor - Implausible Signal
2 Audi models · 2 documented issues
P017B on Audi by model: symptoms, diagnosis and fix
Audi TSB 2062951/4 covers all 2020 RS Q8 vehicles and early-production 2021 vehicles through chassis WUARRDF11MD011353 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 bounded sensor condition does not establish universal turbo-coolant hose, pump or heat-related failure.
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)
Audi TSB 2062951/4 covers all 2020 SQ8 vehicles and early-production 2021 vehicles through chassis WA1CWBF17MD010458 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 bounded sensor condition does not establish universal turbo-coolant hose, pump or heat-related failure.
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)
P017B 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 P017B mean on a Audi?
P017B stands for "Cylinder Head Temperature Sensor - Implausible Signal." The engine control module has compared the cylinder head temperature sensor signal against other thermal models and sensors and found it implausible - the value is out of range, drifting, or inconsistent with expected engine warm-up behaviour. On the Audi 4.0T V8 this is documented in TSB 2062951 (A8, S8, Q7, SQ7, Q8, SQ8, RS Q8, RS 6, RS 7) alongside P218100, where a damaged O-ring lets water into the plastic housing of coolant temperature sender G407 and corrupts the sensing element. The loss of function is often intermittent. On Audi it is documented across 2 models: RS Q8, SQ8.
What are the most common causes of P017B?
The most common causes of P017B are: Damaged O-ring on coolant temperature sender G407 allowing moisture into the sensor housing (Audi TSB 2062951), Failed or drifting cylinder head temperature sensor element, Corroded sensor connector or damaged wiring, Genuine cooling system problem (low coolant, air pocket, failed thermostat or water pump) producing real out-of-range temperatures. The specific cause varies by vehicle.
How much does it cost to fix P017B on a Audi?
Repair costs vary widely with the root cause and Audi model; each issue on this page carries its own estimate where one is published.
Looking for P017B on a different make?
View P017B across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.