Injector Circuit / Open — Cylinder 1
PCM isn't seeing the injector on cylinder 1 respond electrically when it commands it.
What it means (plain English)
The PCM grounds the injector to fire it and watches the voltage signature. If it doesn't see the expected inductive kick when it tries to fire — because the circuit is open, shorted, or the injector coil is dead — it sets P0201. Same code structure for P0202 (cyl 2), P0203 (cyl 3), etc.
What the computer is actually seeing
No or wrong electrical response on the injector driver circuit when commanded. Could be open coil, broken wire, or PCM driver failure.
What a healthy reading looks like
Injector resistance: gas saturated ~12–16 Ω, gas peak-and-hold ~2 Ω, diesel solenoid ~0.5–2 Ω. Driver pulse: square wave whose width = injector pulse width in ms.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Unplug injector and measure coil resistance. Out of spec = bad injector.
- 2Check for power at the connector (key on) — usually battery voltage on one pin.
- 3Back-probe the driver pin while cranking — should see pulses on scope.
- 4Swap injector or connector to another cylinder to confirm.
Common causes
- Failed injector coil (open winding)
- Broken / chafed injector wire
- Corroded or unseated connector
- Failed PCM driver (rare)
Typical repair cost
$80 (gas injector) to $600 (diesel injector + coding).
Related codes
Frequently asked questions
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