U069A: Lost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 3

What it means

Communication with exhaust gas temperature sensor bank 1 sensor 3 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

Exhaust gas temperature sensor bank 1 sensor 3 measures exhaust temperature at its installed point on the bank 1 exhaust system and sends the reading over the vehicle bus. This code sets when communication with that specific sensor is lost, so systems that use its temperature data may substitute an estimate or disable a related function.

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. Record freeze-frame data and scan engine and emissions modules for other exhaust-temperature, aftertreatment, or communication codes.
2. Check live data for bank 1 sensor 3’s communication status and temperature reading, comparing other exhaust-temperature sensors for plausibility.
3. Locate bank 1 sensor 3 using vehicle service information, then inspect its connector and exposed wiring for heat damage, chafing, or corrosion.
4. Check the sensor’s specified power and ground, since a supply fault can prevent the sensor from communicating.
5. Test the bus wiring for an open or short according to the wiring diagram and manufacturer procedures.
6. If the circuit and supply are sound, determine whether bank 1 sensor 3’s module has failed.

Common fixes

• Reconnect or repair the bank 1 sensor 3 connector.
• Repair heat-damaged or chafed bus wiring at bank 1 sensor 3.
• Restore the sensor’s power or ground.
• Replace exhaust gas temperature sensor bank 1 sensor 3 if its circuit and supply are sound and it has failed.

Can I keep driving?

If the engine runs normally and no exhaust-temperature or emissions warning appears, a short trip may be possible, but arrange diagnosis soon. Avoid heavy loads if warnings or reduced power occur, since missing bank 1 sensor 3 data can affect exhaust-temperature protection or aftertreatment control.