Engine

P03CA — Cylinder 6 Pressure Sensor Circuit High

Severity: medium Drive with care, to a shop

What P03CA means

The engine control module is reading a voltage from the cylinder 6 pressure sensor that is above the expected range. This sensor reports combustion pressure, which the ECM can use to fine-tune ignition and fueling. A high signal points to a failed sensor, a wire shorted to voltage, or a fault in the module's input circuit.

Symptoms

  • Check Engine Light on
  • Rough or unstable idle
  • Possible misfire on cylinder 6
  • Loss of power or sluggish acceleration
  • Higher fuel consumption

Possible causes

  1. Failed cylinder 6 pressure sensor
  2. Wiring shorted to voltage or damaged sensor harness
  3. Corroded or loose connector pins
  4. Poor sensor ground or electrical interference
  5. ECM input circuit fault (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data, noting any related codes on other cylinders
  2. Inspect the cylinder 6 sensor connector and harness for damage, moisture and chafing
  3. Check reference voltage and ground at the sensor with a multimeter, following the wiring diagram
  4. Test the signal wire for a short to voltage and for continuity to the ECM
  5. Compare live sensor data with other cylinders on a scan tool
  6. Swap in a known-good sensor, or test the sensor on another cylinder if the design allows
  7. If wiring and sensor check out, test the ECM and look for software updates

Common fixes

  • Replace the cylinder 6 pressure sensor
  • Repair or replace the damaged harness or connector
  • Restore the ground connection and clean contacts
  • Diagnose, reflash or repair the ECM

Questions and answers

What does P03CA mean?

It means the cylinder 6 pressure sensor circuit is sending a high signal. The sensor itself or its wiring is the most common cause.

Can I drive with code P03CA?

Briefly and carefully if the engine runs smoothly. If it misfires or shakes badly, avoid driving to protect the catalytic converter.

How do I clear P03CA?

You can erase it with a scan tool, but it will return until the cause is fixed. Check the sensor, connector and wiring first.

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.