U0620: Lost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 2

What it means

A control module has stopped receiving expected network messages from the exhaust gas temperature sensor on bank 1, sensor 2. The code indicates a communication fault; the effect depends on how the vehicle uses that sensor.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test

How it works

Exhaust gas temperature sensor bank 1 sensor 2 reports exhaust heat at the second monitored position on engine bank 1. U0620 sets when a control module stops receiving that sensor's expected network messages, making its temperature data unavailable for systems that use it.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• Warning light or message related to the affected system
• Exhaust temperature data may be unavailable

How to diagnose it

1. Scan all modules for related network codes and record freeze-frame data to check whether sensor 2 went offline with other faults.
2. Check live data for bank 1 sensor 2 and compare its status with bank 1 sensor 1 and other available exhaust temperature readings.
3. Inspect the bank 1 sensor 2 connector and wiring near the exhaust for heat damage, corrosion, loose pins, or chafing.
4. Check the sensor module's power and ground using the manufacturer's wiring information.
5. Test the network circuit for bank 1 sensor 2 for opens or shorts according to the manufacturer's procedure.
6. If its supply and wiring are good, verify that the sensor module has stopped communicating before replacing it.

Common fixes

• Repair heat-damaged or chafed wiring at bank 1 sensor 2.
• Clean or repair corroded or loose connector terminals.
• Restore the module's power or ground, or repair its network circuit.
• Replace the bank 1 sensor 2 module if wiring and supply tests pass but communication remains absent.

Can I keep driving?

If the vehicle runs normally, a short trip to a repair location is generally reasonable, but avoid sustained heavy load until the missing temperature data is restored. An emissions or aftertreatment warning may appear if a system that depends on this sensor cannot operate correctly.