P0201 - Injector Circuit / Open - Cylinder 1
System
Powertrain (Engine & Gearbox)
Technical Description
The ECM monitors the inductive flyback voltage spike (40-80V) when the injector driver transistor turns off. DTC P0201 triggers when this peak is absent, confirming an open circuit or electrical driver failure on Cylinder 1 injector.
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Injector Coil Resistance at 20°C (68°F) | Resistance (Ω) | 11.5 - 15.5 Ω (Port) / 1.5 - 3.0 Ω (Direct) | Disconnected injector at 20°C |
| Injector Power Supply (Terminal 15/87) | Voltage (V) | 11.8 - 14.4 V | Ignition ON |
| Inductive Flyback Peak Voltage | Voltage (V) | 45 - 80 V | Engine running measured with scope |
Disconnected injector at 20°C
Ignition ON
Engine running measured with scope
Oscilloscope Waveform Analysis
1 ms/div, 20 V/divPossible Causes
Open solenoid winding inside fuel injector
Loose, spread, or corroded connector terminals at injector
Broken driver wire between injector and ECM
Blown injector driver transistor (MOSFET) in ECM
Symptoms
3
Recommended Solution
Disconnect injector 1 connector and measure coil resistance (11-16 Ω). If reading OL, replace injector.
Connect a Noid light to harness plug during cranking to verify ECM driver pulses.
Replace the faulty fuel injector.
Mechanic's Tip
A Noid light plugged into the harness verifies ECM and wiring in seconds. If the light flashes during cranking, the injector solenoid itself is definitely the faulty component.