P001B

What it means

P001B means the engine control unit has detected a low voltage or low signal in the control circuit for the 'A' camshaft profile actuator on bank 1. This actuator switches or adjusts the cam profile (valve lift or duration) on systems that offer it. The control unit sets the code when the circuit voltage or current is not what it expects when it commands the actuator, which points to a short to earth, a wiring fault or a failing actuator or driver.

Symptoms

• Engine warning light on
• Reduced power or flat performance, especially at higher revs
• Rough idle or uneven running
• Poor fuel economy
• Engine may drop into a limited performance mode
• Possible hesitation when the system should change cam profile

Possible causes

• Wiring fault in the actuator control circuit, such as chafing causing a short to earthlikely
• Faulty camshaft profile actuator or solenoid with low internal resistance or a shortlikely
• Damaged, corroded or loose connector at the actuator or control unitlikely
• Low battery voltage or poor earth or power supply to the actuator circuitpossible
• Oil leak or contamination reaching the actuator connector or wiringpossible
• Fault in the control unit output driverrare
• Outdated control unit software where the manufacturer has documented a fix for this faultrare

How to diagnose

1. Read all stored codes and freeze frame data to see engine speed, load, temperature and battery voltage when the fault set, and note any related cam timing or misfire codes.
2. Check engine oil level and condition, as the actuator system relies on correct oil, and check for oil in the actuator connector.
3. Visually inspect the wiring and connector at the bank 1 actuator for chafing, heat damage, corrosion, oil ingress and poor pin tension.
4. Check battery condition and charging voltage, and confirm the actuator power supply and earth are sound.
5. Measure the actuator resistance and compare it with the manufacturer specification, as values depend on the model and engine.
6. With the connector unplugged, check the control wire for a short to earth and continuity back to the control unit.
7. Use a bidirectional test if available to command the actuator and watch the circuit response with a scope or multimeter.
8. Check for manufacturer service bulletins or software updates relating to this code for the specific model and engine.

How to fix

• Repair or replace damaged wiring and fix any short to earth in the control circuit.
• Clean or replace a corroded or damaged connector and terminals.
• Replace the camshaft profile actuator if its resistance or operation is out of specification.
• Correct low battery voltage, charging or earth faults.
• Fix any oil leak affecting the actuator or harness, and change the oil if it is the wrong grade or contaminated.
• Update the control unit software only if the manufacturer lists it as a fix for this fault, and replace the control unit only after all other faults are ruled out.

Can I keep driving?

Nearby codes

• P001AGenericA Camshaft Profile Actuator A Control Circuit/Open Bank 1
• P001CGenericA Camshaft Profile Actuator A Control Circuit High Bank 1