U011B: Lost Communication With Rocker Arm Control Module

What it means

A control module has lost communication with the rocker arm control module. Variable valve operation may be affected on vehicles that use this module.

How it works

The rocker arm control module operates or coordinates variable rocker arm functions on engines equipped with that system. This code sets when another module stops receiving expected messages from it, so variable valve operation or engine performance may be affected.

Common causes

Most likely first.

1. Loss of module power or ground
2. Open, shorted, or damaged communication wiring or connector
3. Module or gateway fault

Symptoms

• Warning lights or messages
• Engine performance may be affected
• Communication faults in other modules

How to diagnose it

1. Scan all modules for U011B and variable valve or engine performance codes, noting which modules cannot reach the rocker arm control module.
2. Review freeze-frame data and symptoms to see whether the fault appeared during startup, under load, or with an engine warning.
3. Inspect the rocker arm control module connector and nearby engine harness for oil contamination, heat damage, looseness, or chafing.
4. Check the module's power and ground circuits against the manufacturer's specification.
5. Test the module's communication wiring for opens, shorts, or poor connections using the wiring diagram.
6. If the circuits pass, use vehicle-specific diagnostics to check the gateway and rocker arm control module operation.

Common fixes

• Repair chafed, heat-damaged, or oil-contaminated wiring at the rocker arm control module.
• Reconnect or repair a loose or corroded module connector.
• Restore a failed power feed or ground to the module.
• Repair a confirmed network or gateway fault, or replace and configure the rocker arm control module if testing confirms failure.

Can I keep driving?

If engine performance is rough, reduced, or accompanied by a warning, avoid hard acceleration and heavy loads until the variable valve system is working correctly. Continued operation with affected valve control can worsen drivability and may cause additional engine faults.