OBD-II code · Network
U0685 Lost Communication With Catalyst Temperature Bank 1 Sensor 2
The vehicle bus reports loss of communication with smart catalyst temperature sensor on bank 1 sensor 2. Catalyst protection and light-off monitoring switch to model-based estimates.
Is it safe to drive with U0685?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Catalyst Temp Sensor Bank 1 Sensor 2, Vehicle Bus Wiring
Related codes
- U0684Lost Communication With Catalyst Temperature Bank 1 Sensor 1
- U0686Lost Communication With Catalyst Temperature Bank 2 Sensor 1
- U0687Lost Communication With Catalyst Temperature Bank 2 Sensor 2
- U0682Lost Communication With Throttle/Pedal Position Sensor/Switch E
- U0683Lost Communication With Throttle/Pedal Position Sensor/Switch F
- U0688Lost Communication With Throttle Position Sensor/Switch G
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.