Engine

P03F3 — Camshaft Profile Actuator B "C" Control Circuit High, Bank 1

Severity: medium Drive with care, to a shop

What P03F3 means

The engine control module monitors the voltage in the control circuit of the camshaft profile actuator, part of the variable valve timing or lift system on bank 1. P03F3 sets when the circuit voltage is higher than expected, which points to an open circuit, a short to power, a failing actuator or a faulty driver in the ECM. The "B" and "C" labels vary by manufacturer, so confirm the exact location in the service information.

Symptoms

  • Check engine light on
  • Hesitation or reduced power
  • Rough idle
  • Worse fuel economy
  • Possible limp mode
  • Unstable rpm when load changes

Possible causes

  1. Failed bank 1 camshaft profile actuator (solenoid) B "C"
  2. Damaged wiring: open, short to power or high resistance
  3. Corroded or damaged actuator connector
  4. Faulty camshaft position sensor
  5. Low or poor-quality engine oil affecting actuator operation
  6. ECM driver fault (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data, clear the code and see if it returns
  2. Inspect the actuator connector and harness for chafing, oil contamination and corrosion
  3. Check oil level and condition, change it if needed
  4. Measure actuator coil resistance and compare with the manufacturer spec
  5. Test the control wire for opens and shorts to power or ground
  6. Check supply voltage and the control signal at the connector with the engine running
  7. Check camshaft and crankshaft sensor signals and their correlation
  8. If wiring and actuator test good, check for ECM software updates and ECM condition

Common fixes

  • Repair the wiring or replace the damaged connector
  • Replace the camshaft profile actuator
  • Change the oil and filter if oil is the cause
  • Replace the camshaft position sensor if it tests faulty
  • Update or replace the ECM as a last resort

Questions and answers

Can I drive with P03F3?

Short trips to a shop are usually fine, but expect reduced power and rough running. Don't put off diagnosis for long.

What most often causes P03F3?

Most often it's a wiring or connector problem at the actuator, or a failed actuator solenoid. Start by inspecting the harness and measuring actuator resistance.

Can I just clear the code?

Clearing it only turns off the light for a while. If the cause isn't fixed, the code will come back.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.