U0687: Lost Communication With Catalyst Temperature Bank 2 Sensor 2

What it means

The vehicle bus reports loss of communication with smart catalyst temperature sensor on bank 2 sensor 2. Catalyst protection and light-off monitoring switch to model-based estimates.

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

Catalyst temperature sensor 2 on bank 2 reports temperature across the vehicle network for catalyst protection and warm-up monitoring. This code sets when messages from bank 2 sensor 2 are no longer received, so the controller may rely on a modeled temperature for that catalyst.

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 all modules for communication faults to establish whether bank 2 sensor 2 or several network devices are affected.
2. Check live data for bank 2 sensor 2 temperature and communication status, comparing it with bank 2 sensor 1 and other available catalyst readings.
3. Inspect the bank 2 sensor 2 connector and nearby bus wiring for heat damage, corrosion, chafing, or loose terminals.
4. Check sensor or module power and ground using the manufacturer's procedure.
5. Test the bus branch for bank 2 sensor 2 for opens or shorts, then assess the sensor or module if wiring and supplies pass.

Common fixes

• Secure or clean the bank 2 sensor 2 connector.
• Repair damaged bus wiring or terminals near bank 2 sensor 2.
• Restore a faulty power or ground connection to the sensor or module.
• Replace bank 2 sensor 2 or its module if testing confirms an internal communication failure.

Can I keep driving?

A short, gentle drive may be possible if the vehicle operates normally, but catalyst temperature monitoring and protection may use an estimate for bank 2. Avoid heavy loads until diagnosed and stop if warning lights or drivability problems worsen.