What it means
The ECM detects a low fault on the 14 volt power module current sensor b circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Current Sensor B monitors current in the 14-volt power module, and the engine control module uses that signal to assess low-voltage system operation. This code sets when the Sensor B circuit signal falls below the expected electrical range, which may indicate a short to ground, a sensor fault, or poor terminal contact.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or hybrid-system warning light on
- Charging-system warning light may come on
- Charging or 12-volt system performance may be affected
How to diagnose it
- Use a compatible scan tool to record freeze-frame data and check whether the Sensor B signal is unusually low or fixed.
- Check for related charging-system codes and any 12-volt warning symptoms that occurred when the fault set.
- With the vehicle switched off, inspect the Sensor B connector and harness for corrosion, loose pins, damaged insulation, or a wire contacting ground.
- Test the Sensor B signal circuit for a short to ground and poor terminal contact using the wiring diagram and manufacturer's procedure.
- If the circuit passes, test Current Sensor B and replace it only if it fails the specified checks.
Common fixes
- Repair Sensor B wiring that is shorted to ground.
- Clean or repair corroded or high-resistance terminals at the Sensor B connector.
- Replace Current Sensor B if testing confirms an internal fault.
- Clear the code and verify that the current signal and charging operation are plausible.
Can I keep driving?
A low Sensor B signal can interfere with 12-volt charging control and may leave the vehicle with insufficient electrical power. Limit driving if the charging warning is on, and stop safely if electrical systems weaken or the vehicle reports a power-system fault.
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.