Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / P1204 — Injector charge problem(over)

P1204 — Injector charge problem(over)

Detailed page for trouble code P1204.

34,428codes
59brands
11,925generic
22,503specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

P1204

MITSUBISHI P — Powertrain

Injector charge problem(over)

Brand: MITSUBISHI
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck‑open or mechanically leaking fuel injector(s)
  • Injector electrical short (stuck ON) or short to battery
  • ECU commanding excessive pulse width due to sensor input (coolant temp, MAF, MAP, TPS)
  • High fuel rail pressure or faulty fuel pressure regulator (over‑pressure)
  • Incorrect injector calibration / wrong injectors installed
  • Wiring harness damage, chafing or poor connector causing incorrect signals

Symptoms

  • Check Engine Light with P1204 stored
  • Rich running: black smoke from exhaust, strong fuel smell
  • Poor fuel economy
  • Rough idle, misfire or sluggish acceleration
  • Hard starting or flooding on hot start
  • High short‑term/long‑term fuel trim (positive or negative depending on how ECU compensates)

What to check

  • Read freeze frame and related codes (P02xx injector circuit codes, P0172/P0174, misfire codes)
  • Visual inspection of injector harness, connectors and engine grounds for damage or corrosion
  • Measure injector resistance and compare across all cylinders
  • Backprobe injector connector to verify constant supply voltage (~battery voltage) and pulsed ground during cranking/running
  • Use a lab scope to view injector waveform and duty cycle on suspected cylinders
  • Perform fuel pressure test at idle and cranking; inspect for overpressure

Signal parameters

  • Injector supply voltage: ~12 V (key ON) — should be battery voltage at connector pin
  • Injector coil resistance: model dependent; low‑impedance injectors ~1–3 Ω, high‑impedance ~10–16 Ω (compare all cylinders)
  • Typical idle injector pulse width: ~2–5 ms (varies by engine and temp)
  • High‑load pulse width: >10 ms possible near full load
  • Injector duty cycle: normally
  • Fuel rail pressure (typical gasoline MPI): ~300–450 kPa (43–65 psi) — varies by engine

Diagnostic algorithm

  1. Retrieve freeze frame and all stored/ pending codes. Note engine conditions when code set.
  2. Inspect wiring, connectors and grounds for the injector(s) indicated or for all cylinders if not specified.
  3. Measure injector coil resistance for each injector; flag units that differ significantly from the others or from spec.
  4. With a voltmeter or scope backprobe the injector connector: verify constant battery voltage at the supply pin with key ON and verify pulsed ground (or pulsed positive, depending on design) during cranking/engine run.
  5. Use an oscilloscope to check injector drive waveform (look for unusually long pulse widths, stuck ON pattern, or noise).
  6. Perform a fuel rail pressure test at idle and under load; compare to specification and check regulator operation.
  7. Conduct an injector balance/flow test or cylinder cut‑out test to confirm excessive flow on the suspect injector(s).
  8. Swap suspect injector(s) with a known good cylinder to see if overcharge code or symptoms follow the injector.
  9. Check related sensor inputs (MAF, MAP, engine coolant temp, throttle position) and verify they are within expected ranges; replace or calibrate if faulty.
  10. If wiring and injectors check OK, inspect ECU outputs and driver circuitry; consider ECU replacement or reprogramming only after confirming harness and injectors are good.
  11. Clear codes and perform road test to confirm repair. Re-scan to ensure code does not return.

Likely causes

  • One or more injectors stuck open or internally shorted
  • Injector supply circuit shorted to battery (constant feed) or ground driver stuck on
  • Fuel rail pressure regulator failure producing excessive rail pressure
  • Faulty sensor (CTS, MAF, MAP) causing ECU to over‑command fuel
  • Damaged wiring/connector to injectors or poor ground

Fault status

⚠️ Status
P1204 — Injector charge problem (over). ECU detected injector on‑time, duty cycle or delivered fuel higher than expected for at least one cylinder. May cause rich running, black smoke and poor fuel economy.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours
406

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

MITSUBISHI

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .