U068D: Lost Communication With EGR Temperature Sensor A

What it means

The vehicle bus reports loss of communication with smart EGR temperature sensor A (typically pre-cooler). EGR cooling diagnostic switches to model-based estimation.

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

EGR temperature sensor A is a smart sensor that reports temperature, typically before the EGR cooler, over the vehicle communication bus. This code sets when the bus loses its messages, so the EGR cooling diagnostic estimates temperature instead of using sensor A's live 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. Save freeze-frame data and scan all modules for communication codes to identify when EGR temperature sensor A went offline and whether other devices share the fault.
2. Inspect the sensor A connector and wiring at the pre-cooler area for loose pins, corrosion, heat damage, or chafing.
3. Check the sensor module's power and ground using the manufacturer's procedure, as a supply fault can interrupt communication.
4. Inspect the bus wiring and splices serving sensor A for opens or shorts, then test the circuit as the manufacturer specifies.
5. If the circuit and supply are sound, confirm with a capable scan tool that sensor A does not communicate before replacing the sensor/module.

Common fixes

• Reconnect or repair the pre-cooler sensor A connector and damaged terminals.
• Repair an open, short, or damaged splice in the sensor A communication wiring.
• Restore the sensor module's power or ground.
• Replace EGR temperature sensor A if it remains offline with good wiring, power, and ground.

Can I keep driving?

If the engine runs normally and no overheating or exhaust warnings appear, a short gentle trip is usually reasonable, but avoid heavy loads until the EGR temperature signal is restored. Delayed repair can leave EGR cooling diagnostics relying on estimates and may affect emissions control.