What it means
The third actuator supply rail is below the expected voltage. Battery weakness, blown fuse, or excessive current draw collapses the supply.
At a glance
- Usually lights the check-engine light
How it works
Actuator supply voltage C is a shared power feed for actuators connected to that rail. This code sets when the control module detects that the rail voltage is below its expected range, which can leave one or more actuators slow or inoperative.
Common causes
Most likely first.
- Load on the rail shorted to ground
- Battery condition causes voltage to drop
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- One or more actuators may operate slowly or not switch
How to diagnose it
- Record freeze-frame data and scan for related actuator codes to identify which rail C loads may be affected.
- Check battery condition and charging-system data during the conditions shown in the freeze frame.
- Inspect the rail C fuse, relay, connectors, and shared supply wiring for corrosion, heat damage, or loose terminals.
- Measure voltage at the rail C feed and affected actuator connectors under load, then compare with the manufacturer's specification.
- If the supply path is sound, isolate rail C loads to find a shorted actuator or wire pulling the shared voltage down.
Common fixes
- Repair corroded or loose terminals in the rail C supply path.
- Repair a damaged supply wire or replace a faulty fuse or relay.
- Address a weak battery or charging-system fault if testing confirms it.
- Replace a shorted actuator only after confirming it is pulling down rail C.
Can I keep driving?
Avoid hard acceleration if actuators are operating slowly or the engine has reduced power. Stop if engine operation becomes unstable or a temperature warning appears, since affected actuators may disrupt engine control.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.