P0CA0

What it means

P0CA0 is a generic powertrain code meaning the control unit has detected an intermittent fault in the circuit of current sensor B on the 14 volt power module. The signal from the sensor has dropped out, jumped or gone implausible for short periods rather than failing permanently. The exact location and function of the 14 volt power module depends on the vehicle, and it is typically found on hybrid or mild hybrid systems.

Symptoms

• Warning light on, possibly a hybrid or charging system warning as well
• Intermittent loss of auxiliary battery charging or a flat 12 volt battery
• Stop-start or hybrid assist not working at times
• Flickering lights or electrical glitches that come and go
• Reduced performance if the system limits output
• No obvious symptoms other than a stored code

Possible causes

• Loose, corroded or damaged connector at the current sensor or power modulelikely
• Chafed, broken or high-resistance wiring in the sensor signal, reference or ground circuitlikely
• Poor battery or earth connections causing unstable voltage to the sensorpossible
• Failing current sensor, either separate or built into the power modulepossible
• Internal fault in the 14 volt power module (DC-DC converter) or its control unitpossible
• Outdated control unit software where the manufacturer has issued a fix for this faultrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting when the fault occurred and the system voltage
2. Check the 12 volt battery condition and charging voltage, and look for other voltage or communication codes
3. Inspect the sensor and power module connectors and wiring for corrosion, water ingress, chafing and loose pins
4. Check the battery terminals and main earth and power connections for tightness and corrosion
5. Wiggle-test the harness and connectors with live data on screen to see if the current reading drops out or jumps
6. Measure the sensor supply, reference and ground and check the signal circuit for resistance and shorts, following the manufacturer's wiring diagram
7. Compare the live current reading with a known good clamp measurement, where the procedure allows
8. Check for software updates or technical bulletins for the specific model and engine

How to fix

• Clean, secure or replace the affected connectors and terminals
• Repair or replace damaged wiring in the sensor circuit
• Repair battery and earth connections and replace the battery if it is weak
• Replace the current sensor or the 14 volt power module if testing shows it is faulty
• Update the control unit software if an applicable update exists for a known fault
• Clear the code after repair and road test to confirm it does not return

Can I keep driving?

Nearby codes

• P0C9FGeneric14 Volt Power Module Current Sensor B Circuit High
• P0CA1GenericDrive Motor Control Module Requested MIL Illumination