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P1234

Injector Circuit Cylinder 5 Intermittent.

  • Chrysler
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
2
AreaFuel and air metering (injector circuit)
34
FaultThe specific fault in that area

What it means

P1234 on a Chrysler means the engine control unit has detected an intermittent fault in the fuel injector circuit for cylinder 5. The control unit monitors the injector driver and circuit, and saw a signal that was briefly open, shorted or out of range rather than a constant failure. Because it comes and goes, the fault may not be present when the car is inspected.

Symptoms

  • Engine misfire or rough running on cylinder 5, often intermittent
  • Hesitation or stumbling under load
  • Engine management light on
  • Occasional rough idle or poor fuel economy
  • Intermittent hard starting or stalling

Possible causes

  • Loose, corroded or damaged connector at the cylinder 5 injectorlikely
  • Chafed, stretched or broken wiring in the injector harness for cylinder 5, intermittently open or shortinglikely
  • Failing cylinder 5 fuel injector with an intermittent internal winding faultpossible
  • Poor power or earth supply to the injector circuit, such as a loose connection or blown fusepossible
  • Fault in the engine control unit injector driverrare
  • Water ingress or heat damage to the harness or connector near the enginerare

How to diagnose

  1. Read all stored and pending codes and note freeze frame data, including engine speed, load and temperature when the fault set
  2. Check for other misfire or injector codes, which may show whether the fault is limited to cylinder 5
  3. Visually inspect the cylinder 5 injector connector and harness for damage, heat, rubbing, corrosion and bent or loose terminals
  4. Wiggle test the harness and connector with the engine running, watching for misfire or changes in live data
  5. Measure the injector winding resistance and compare it with the specification for that engine, as values vary by model
  6. Check the injector power supply, earth and related fuses against the wiring diagram for that model
  7. Use a suitable scope or test lamp to confirm the control unit is sending a steady injector pulse to cylinder 5
  8. Check for software updates or technical bulletins for that model, as procedures vary by engine

How to fix

  • Clean, repair or replace the injector connector and terminals if they are corroded or loose
  • Repair or replace the damaged section of injector wiring, using proper solder and sealed joints or the correct repair method
  • Replace the cylinder 5 injector if its resistance or operation is out of specification
  • Restore the power or earth supply by repairing connections or replacing any faulty fuse or relay
  • Replace or repair the engine control unit only after the wiring and injector have been proven good and the driver fault is confirmed

Can I keep driving?

Medium severity

The car can usually be driven for a short time to get it checked, but a misfiring cylinder can overheat the catalytic converter and cause stalling. Avoid heavy loads and have it fixed soon, and stop driving if the engine misfires badly or the warning light flashes.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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