U011A: Lost Communication With Exhaust Gas Sensor Module

What does U011A mean?

U011A is a diagnostic trouble code indicating "Lost Communication With Exhaust Gas Sensor Module". The vehicle's main computer has lost its ability to communicate with a specific module over the data bus. This could be caused by a wiring fault, a blown fuse, or a failed control module.

Symptoms you may notice

• Check engine light (MIL) illuminated on dashboard
• Intermittent warning lights
• Erratic gauge readings

Common causes

• Failed control module
• CAN bus wiring fault or short
• Blown fuse to the affected module
• Water intrusion in a connector or module
• Battery voltage too low

What should you do?

This code sits in an engine peripheral, typically emissions or forced induction. It will not take braking or steering away, but it can put the car into limp mode, cost you fuel and fail a roadworthy. Book it in rather than clearing it and hoping.