P017B: Cylinder Head Temperature Sensor - Implausible Signal
2 vehicles · 1 makes
Most Reported On
P017B is an OBD-II diagnostic trouble code meaning “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. This code is most commonly reported on 2020-2021 Audi RS Q8, and 2020-2021 Audi SQ8.
Common Causes
Diagnostic Tools
This is a powertrain code, so a basic OBD-II reader can read it. These read P017B.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple code reader for engine (P) codes on many compatible OBD-II vehicles. It does not support every vehicle or hybrid/EV application, and it does NOT read body, chassis or network codes; confirm exact-vehicle compatibility before buying.
- Read & clear engine (P) codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth scanner with a companion app that reads beyond the engine module — ABS, SRS and transmission — plus manufacturer-specific codes on many vehicles.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X V3.0 Elite OBD-II Scanner
by LAUNCH
Handheld scanner covering the four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level tablet with all-system coverage and bi-directional control, so you can command a module rather than only read it.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
What you can do yourself, and what needs a shop
Reading the code, clearing it, and watching whether it returns is a driveway job with the right scanner. These steps are not:
- Module programming or software updates — needs the manufacturer software or a J2534 pass-through with a paid subscription.
- Replacing a control module — most are VIN-programmed and immobilizer-registered, so a new one does nothing until it is coded to your car.
- Airbag/SRS component work — a stored fault can deploy a live device.
If the vehicle is still under warranty, check for an open recall or technical service bulletin before buying anything — the repair may already be covered.
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FAQ
What does P017B mean?
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.
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?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P017B?
Au7o has documented P017B across 2 vehicle models from 1 manufacturers: Audi.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.