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Home / DTC / P0201 — No.1 injector system

P0201 — No.1 injector system

Detailed page for trouble code P0201.

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Code

P0201

MITSUBISHI P — Powertrain

No.1 injector system

Brand: MITSUBISHI
Type: P — Powertrain
Views: UK: 23 EN: 131 RU: 116
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Page language: EN

Causes

  • Open or short in injector #1 wiring (connector, harness, chafing).
  • Poor or corroded connector/terminal at injector or ECM.
  • Failed fuel injector (coil open or shorted, stuck).
  • Blown fuse, faulty fuel injector relay, or loss of injector supply voltage.
  • Faulty ECM/PCM driver circuit.
  • Aftermarket wiring, engine work or contamination causing short to ground or power.

Symptoms

  • Check Engine Light (MIL) illuminated with P0201 stored.
  • Rough idle or vibration from the engine.
  • Single-cylinder misfire (misfire felt from cylinder 1).
  • Poor acceleration, reduced power and fuel economy.
  • Hard starting or longer cranking time.
  • Increased exhaust emissions or failed emissions test.

What to check

  • Read freeze-frame and live data with a scan tool; confirm P0201 and note engine conditions.
  • Visually inspect injector #1 connector, pins and wiring for damage, corrosion or loose fit.
  • Check relevant fuses and fuel injector relay for proper operation.
  • Backprobe injector connector to verify supply voltage and control signal while cranking/run.
  • Measure injector coil resistance with a multimeter (engine off).
  • Wiggle wiring harness while monitoring code or injector operation to find intermittent faults.

Signal parameters

  • Injector supply voltage: approximately battery voltage (12 V) present at the injector power pin with ignition ON (varies by model).
  • Injector driver behavior: PCM typically grounds the injector to pulse; control pin will switch between ~0 V (grounded) and near battery voltage when not driven.
  • Injector coil resistance: varies by design — common ranges are low-impedance ~2–5 Ω or high-impedance ~10–16 Ω. Check the vehicle service manual for the exact spec.
  • Typical pulse width: idle/load conditions commonly 2–6 ms; varies by RPM/load and model — use live data/oscilloscope for verification.
  • Current draw: depends on injector impedance; abnormal open (= infinite Ω) or short (< expected) indicates fault.

Diagnostic algorithm

  1. Verify code and conditions: connect a scanner, record freeze-frame and live data. Note if multiple injector/cylinder codes present.
  2. Visually inspect harness, connector and pins at injector #1 and at the ECM for corrosion, damage, melted insulation or poor crimps.
  3. With ignition OFF, disconnect the injector connector and measure injector coil resistance. Compare to factory specification.
  4. With ignition ON (engine not running), verify that battery voltage is present at the injector supply pin(s).
  5. Crank engine or run while backprobing the injector control pin; using a multimeter/oscilloscope check for pulsed ground signal from ECM. Look for consistent pulses and correct voltage levels.
  6. Wiggle harness and connectors while watching live data and/or scope for intermittent faults.
  7. If injector resistance and wiring checks are good, swap injector #1 with a known-good injector from another cylinder and see if the code or misfire follows the injector.
  8. If the problem follows the injector, replace the injector. If the problem stays on cylinder 1, continue tracing wiring to ECM and check grounds, fuses and relays.
  9. If wiring and injector are good but no control signal, inspect ECM connector and test ECM driver output; repair or replace ECM only after confirming driver failure per manufacturer procedures.
  10. After repairs, clear codes and test-drive; verify code does not return and that misfire/driveability is corrected.

Likely causes

  • Corroded or loose injector connector at cylinder 1.
  • Broken or damaged wire between injector #1 and ECM (open or short).
  • Faulty injector coil (open or shorted).
  • Faulty ground or low battery/poor supply to injector rail.
  • ECM driver transistor failure (less common).

Fault status

⚠️ Status
P0201 - No.1 injector system malfunction (injector circuit open/short or control fault).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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