U0692: Lost Communication With Exhaust Pressure Sensor B

What it means

The vehicle bus reports loss of communication with smart exhaust pressure sensor B (typically post-DPF or post-turbine). Pressure-based diagnostics switch to a model-based estimate.

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 pressure sensor B is a smart sensor that typically measures pressure after the DPF or turbine and reports it over the vehicle bus. This code sets when the bus loses sensor B's messages, so pressure-based diagnostics must rely on a modeled estimate instead of the post-component 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 see when post-DPF or post-turbine sensor B went offline and whether other bus faults are present.
2. Inspect sensor B's exhaust-side connector and harness for loose pins, corrosion, heat damage, or chafing.
3. Check the sensor module's power and ground using the manufacturer's procedure to rule out a lost supply or ground.
4. Inspect the communication wires and splices serving sensor B for opens or shorts, then test the circuit as specified by the manufacturer.
5. If wiring, power, and ground are sound, use a capable scan tool to confirm sensor B is unreachable before replacing its module.

Common fixes

• Reconnect or repair sensor B's loose, corroded, or heat-damaged connector.
• Repair an open, short, or damaged splice in the sensor B communication wiring.
• Restore the sensor module's power or ground.
• Replace exhaust pressure sensor B if it remains offline after the circuit checks pass.

Can I keep driving?

A brief, gentle drive may be possible if the vehicle runs normally, but avoid towing and heavy loads, particularly with DPF or exhaust warnings. The missing post-DPF or post-turbine pressure reading can affect emissions diagnostics and exhaust-system monitoring, so arrange repair soon.