U0620 code meaning
Lost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 2
Network system Generic code U06xx codes Check engine light
What U0620 means
Sensor 2 on bank 1 is the next exhaust temperature measuring point downstream of sensor 1; on diesels it usually sits ahead of the particulate filter or the SCR catalyst, depending on how the maker numbers its sensors. U0620 is the lost-communication code for this point when it is a digital sensor: its frames have stopped, are too old, or its own diagnosis has switched the SENT output off. GM uses it in the same 2025 diesel tables as U061F with an identical rule (19 bad out of 25 samples at 100 ms, Type A), and again a second code identifies the controller input the sensor is connected to. Monitors and regeneration decisions that need this temperature cannot use it while the link is down. An analog sensor at the same position reports circuit faults as P2031 to P2033.
U0620 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0620
- Malfunction indicator lamp in the first trip on GM diesels
- Diesel particulate filter or SCR warnings may follow
Common causes of U0620
- Most likelySignal, supply or ground wire of the sensor damaged near the exhaust
- PossibleMoisture or corrosion in the underbody connector
- PossibleSensor electronics module failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Egt sensor bank 1 sensor 2Sensor wiring
What each part of U0620 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 20 | The exact fault in that area. |
What to do next
- Note U0620 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 U0620
What does U0620 mean?
U0620 means "Lost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 2". Sensor 2 on bank 1 is the next exhaust temperature measuring point downstream of sensor 1; on diesels it usually sits ahead of the particulate filter or the SCR catalyst, depending on how the maker numbers its sensors. It is a generic code, so it means the same on every make.
Is it safe to drive with U0620?
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 U0620 fail an emissions test?
Yes, it can. U0620 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 U0620 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U0620 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.