Powertrain, generic · Fuel and air metering (injector circuit)

P0203 Cylinder 3 Injector A Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0203 reports an electrical fault, mainly an open circuit, in the injector circuit of cylinder 3. The engine module watches each injector output: GM flags an open circuit at an impedance of 200 kΩ or more – on direct injection and diesel engines in 10 of 20 or 5 of 10 samples and with the warning light in the first trip, on some port-injected engines only after two trips. Ford's port injection reads a fault bit from the driver chip that covers open, short to ground and short to voltage alike; Ford diesels report only the open circuit here and shorts as P0267/P0268. On direct injection the affected injector is switched off; the cylinder misfires.

Likely causes

Connector at the cylinder 3 injector loose, corroded or with a broken or pushed-back pin
Injector coil open
Wire between module and injector open or chafed (heat, rodents)
Injector supply missing (fuse, relay) – then usually several cylinders at once
Driver stage in the engine module faulty

Symptoms

  • Check engine light on
  • Misfire and rough running, misfire code P0303
  • Loss of power, rough idle
  • Limp mode possible on diesel and direct injection

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–700
Time0.5–4 h

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

What to check first

  1. Inspect the injector connector
  2. Measure injector resistance
  3. Check for power and switching at the connector

Parts involved

fuel injector cylinder 3injector wiringengine control module

Related codes

P0267P0268P02F0P0303P0300P020C

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com.