OBD-II code · Network
U0621 Lost Communication With Exhaust Gas Temperature Sensor Bank 2 Sensor 1
The vehicle bus reports loss of communication with smart exhaust gas temperature sensor bank 2 sensor 1 (typically pre-cat). Catalyst protection and DPF regeneration logic switch to model-based estimates.
Is it safe to drive with U0621?
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
- Egt Sensor Bank 2 Sensor 1, Vehicle Bus Wiring
Related codes
- U061FLost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 1
- U0620Lost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 2
- U0622Lost Communication With Exhaust Gas Temperature Sensor Bank 2 Sensor 2
- U069ALost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 3
- U069BLost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 4
- U069CLost Communication With Exhaust Gas Temperature Sensor Bank 2 Sensor 3
- U069DLost Communication With Exhaust Gas Temperature Sensor Bank 2 Sensor 4
- U061ELost Communication With Battery Isolation/Voltage Stabilization Control Module
- U0623Lost Communication With Coolant Pump A
- U0624Lost Communication With Coolant Pump B
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.