Powertrain, generic · Ignition system or misfire

P03F9 B Camshaft Position Actuator Position Sensor C Circuit High Bank 1

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

On some engines the exhaust cam phaser (camshaft position actuator B) has its own position sensors, which tell the engine module where the phaser actually is; sensor C is the third of them, bank 1 the side with cylinder 1. This is a different family from the sliding-cam position sensors (P2C05 ff). P03F9 means the signal stays above its upper limit – typically an open sensor ground, a signal wire shorted to 5 V or battery voltage, or a faulty sensor. No manufacturer document available to us uses this code (GM, Ford and FCA tables checked); the intake counterpart P03E5 ff is equally unused. The phaser is then usually held in its base position.

Likely causes

Sensor ground open or signal wire shorted to 5 V or battery voltage
Sensor faulty
Connector wet or corroded
Engine module

Symptoms

  • Check engine light on
  • Exhaust cam phasing held in its base position, loss of power
  • Possibly rough idle or poorer emissions

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–700
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cam phaser position sensor ccam phaser exhaust bank1sensor wiringengine control module

Related codes

P03F6P03F7P03F8P03E8P2B4AP0014

References: law.cornell.edu, patents.google.com.