Parts
$15–80 per injector
P0203 — Injector Circuit Malfunction — Cylinder 3
STOPIs it safe to drive? A dead cylinder on cylinder 3 will cause rough running and rapid catalytic converter damage — diagnose before driving more than necessary.
What P0203 means
Electrical fault detected in the cylinder 3 injector circuit. The injector may be getting no signal, no power, or may be shorted and drawing too much current.
Most likely causes (in order)
- Failed fuel injector for cylinder 3
- Open circuit in wiring or a corroded connector at cylinder 3
- Short to ground on the injector signal wire
- Wiring harness damage (heat or abrasion near exhaust or valve cover)
- PCM driver failure (uncommon)
Symptoms you might notice
- Misfire on cylinder 3 (P0303 typically also set)
- Engine vibration at idle
- Loss of power
- Possible raw fuel smell if injector is stuck open
What to check first
Use a noid light — a small test light that plugs into the injector harness connector while the engine cranks. If the noid light pulses, the ECU is commanding the injector; resistance-test the injector itself to confirm it's bad. If the noid light doesn't pulse, the fault is upstream — wiring, fuse, or PCM driver.
Repair cost & difficulty
Labor
0.5–2.0 hr
Difficulty
Moderate