U069D: Lost Communication With Exhaust Gas Temperature Sensor Bank 2 Sensor 4

What it means

Communication with exhaust gas temperature sensor bank 2 sensor 4 has been lost. The resulting effects depend on how the vehicle uses that sensor’s data.

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

The exhaust gas temperature sensor at Bank 2, Sensor 4 reports temperature data over a vehicle communication bus. A receiving module sets U069D when messages from that specific sensor stop arriving; the effects depend on which exhaust or emissions functions use its reading.

Common causes

Most likely first.

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

How to diagnose it

1. Scan all modules for communication codes and check the freeze-frame data to see when the Bank 2 Sensor 4 messages stopped.
2. Use the scan tool to check whether Bank 2 Sensor 4 is listed as online and whether its reported temperature is available.
3. Inspect the sensor connector and its harness for loose pins, corrosion, heat damage, chafing, or an open or shorted bus wire.
4. Check the sensor or associated module's power and ground circuits under the conditions specified by the manufacturer.
5. Test bus continuity and shorts on the affected network using the manufacturer's procedure, then assess the sensor module only after wiring and supplies pass.

Common fixes

• Reconnect or repair damaged wiring at the Bank 2 Sensor 4 connector and harness.
• Repair an open or short in the communication bus serving the sensor.
• Restore the sensor module's power or ground by repairing its circuit or replacing a failed fuse.
• Replace the Bank 2 Sensor 4 module if its bus wiring, power, and ground are correct but it still does not communicate.

Can I keep driving?

If the vehicle runs normally and no other warnings appear, a short trip to diagnose it may be reasonable, but avoid heavy loads or long trips because exhaust temperature monitoring may be impaired. Stop if the vehicle loses power, enters limp mode, or shows an overheating or emissions-system warning.