U0621 code meaning
Lost Communication With Exhaust Gas Temperature Sensor Bank 2 Sensor 1
Network system Generic code U06xx codes Check engine light
What U0621 means
U0621 mirrors U061F on bank 2: messages from the first exhaust temperature sensor of the second cylinder bank no longer reach the controller, so the code only appears on V engines or other layouts with two exhaust paths. Bentley documents it for the V8 in the Continental GT, GTC and Flying Spur, model years 2020 to 2023 (bulletins 2065698/1 and 2065698/2): the emission warning lamp is lit and the fault memory shows U0621, often alongside U061F, as intermittent or static. The cause was the sensor harness routed close to the subframe and worn through on a bracket inside the wheel-arch liner; the repair is mending the wires and re-securing them so they cannot touch nearby parts again. GM's SENT diesel tables contain no bank 2 code. Analog circuit faults at this position are P0547 to P0549.
U0621 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0621
- Emission warning lamp on
- Code logged as intermittent first, later static
Common causes of U0621
- Most likelyHarness rubbed through on the subframe or a wheel-arch bracket
- PossibleElectronics of the bank 2 sensor failed
- Less likelyConnector not latched or corroded
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Egt sensor bank 2 sensor 1Sensor wiring
What each part of U0621 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 21 | The exact fault in that area. |
What to do next
- Note U0621 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0621
What does U0621 mean?
U0621 means "Lost Communication With Exhaust Gas Temperature Sensor Bank 2 Sensor 1". U0621 mirrors U061F on bank 2: messages from the first exhaust temperature sensor of the second cylinder bank no longer reach the controller, so the code only appears on V engines or other layouts with two exhaust paths. It is a generic code, so it means the same on every make.
Is it safe to drive with U0621?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U0621 fail an emissions test?
Yes, it can. U0621 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0621 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U0621 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.