What Does U011B Mean?
The PCM has lost communication with rocker arm control module A. This module controls variable valve timing actuators or cylinder deactivation systems on advanced engines.
Common Causes
35%
Faulty rocker arm control module A
30%
Damaged wiring harness or connectors to module A
20%
CAN bus or communication network fault
10%
Power supply or ground circuit issue to module A
5%
PCM software needs update or PCM failure
Diagnostic Steps
1
Step 1: Verify battery voltage and inspect all engine ground connections
2
Step 2: Locate rocker arm control module A (typically on valve cover or engine head) and inspect connectors for oil intrusion, corrosion, or damage
3
Step 3: Check power and ground circuits at module A connector using multimeter and wiring diagram
4
Step 4: Test CAN bus communication signals at module connector with oscilloscope or multimeter
5
Step 5: If all circuits test good but communication lost, replace rocker arm control module A
Estimated Repair Cost
$250 - $1,000
Parts + labor, varies by vehicle and location
The PCM has lost communication with rocker arm control module A. This module controls variable valve timing actuators or cylinder deactivation systems on advanced engines.
The most common cause of U011B (Lost Communication With Rocker Arm Control Module "A") is: Faulty rocker arm control module A
Typical repair costs for U011B range from $250 to $1,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Engine may run rough, lack power, or have reduced fuel economy. Cylinder deactivation will not function. Generally safe to drive but should be repaired promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U011B to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Network
System
Engine Valvetrain / Variable Valve Timing
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
