U011C code meaning
Lost Communication With Rocker Arm Control Module B
Network system Generic code U01xx codes Check engine light
What U011C means
U011C is the partner of U011B for rocker arm control module B, for example the controller of the second cylinder bank or of a second group of switchable rocker arms where the task is split across two units. The engine controller expects cyclic status from it, such as the confirmed lock state per cylinder, and records U011C once those frames fail to arrive. No manufacturer documents this code publicly, and it remains open which production engines use a separate B module at all; the entry relies on CARB's call for separate lack-of-communication codes and its monitoring rules for valve lift and control. Invalid data from this module is U041D. Without the B unit the affected cylinders usually stay in full-lift mode: MIL, possibly uneven running and more fuel.
U011C at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of U011C
- MIL on
- Affected cylinders remain in full-lift mode
- Uneven running or higher consumption
Common causes of U011C
- Most likelyModule B without power or ground
- PossibleContaminated or loose connector at the second cylinder head
- PossibleOpen or shorted CAN lines to module B
- Less likelyRocker arm control module B internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Rocker arm module bCAN bus wiring
What each part of U011C means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1C | The exact fault in that area. |
What to do next
- Note U011C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U011C
What does U011C mean?
U011C means "Lost Communication With Rocker Arm Control Module B". U011C is the partner of U011B for rocker arm control module B, for example the controller of the second cylinder bank or of a second group of switchable rocker arms where the task is split across two units. It is a generic code, so it means the same on every make.
Is it safe to drive with U011C?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U011C fail an emissions test?
Yes, it can. U011C is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U011C to fix?
Difficulty: medium. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will U011C clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.