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P1202

Injector Circuit Open / Shorted - Cylinder #2.

  • Other
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
2
AreaFuel and air metering (injector circuit)
02
FaultThe specific fault in that area

What it means

P1202 is a manufacturer-specific code that, for this entry, means the engine control unit has detected an open or shorted circuit in the cylinder 2 fuel injector. The control unit monitors the injector driver circuit and sets the code when the current or voltage does not match what it expects. The exact test and wiring layout vary by manufacturer and engine, so check the vehicle-specific data.

Symptoms

  • Engine management light on
  • Rough idle or misfire on cylinder 2
  • Hesitation or loss of power under load
  • Hard starting or extended cranking
  • Raised fuel consumption
  • Engine running in a reduced-performance mode on some models

Possible causes

  • Faulty cylinder 2 injector with an open or shorted coil windinglikely
  • Damaged, chafed or corroded wiring between the injector and the control unitlikely
  • Loose, corroded or water-damaged injector plug or control unit connector pinslikely
  • Short to earth or to supply voltage in the injector feed or control wirepossible
  • Blown fuse or faulty relay supplying the injector circuit (depends on model)possible
  • Failed injector driver inside the engine control unitrare

How to diagnose

  1. Read all stored and pending codes and the freeze frame data, noting engine speed, load and temperature when the fault set, and look for related misfire codes.
  2. Visually inspect the cylinder 2 injector plug, the harness route and nearby connectors for chafing, heat damage, oil contamination, corrosion or poor pin tension.
  3. Check the relevant fuses and relays against the wiring diagram for the specific model and engine.
  4. Clear the code and see if it returns immediately or only when the engine is hot or vibrating; wiggle the harness while monitoring for changes in idle quality.
  5. Measure the cylinder 2 injector coil resistance and compare it with the manufacturer's specification, and with the other injectors.
  6. Check the injector supply voltage and the control wire for continuity, and for shorts to earth or to voltage, with the connectors disconnected.
  7. Use an oscilloscope or the manufacturer's diagnostic function to confirm that the control unit is producing the injector drive signal.
  8. Only if the wiring and injector test good, check the control unit driver output and connector, following manufacturer procedures.

How to fix

  • Replace the cylinder 2 injector if its resistance or operation is out of specification, following the correct sealing and fitting procedure.
  • Repair or replace damaged wiring sections, using proper soldered and sealed joins rather than twisted joints.
  • Clean, re-pin or replace corroded or loose connectors and fix any water ingress.
  • Replace a faulty fuse or relay after finding out why it failed.
  • Repair or replace the engine control unit only after confirming the driver fault, and have it programmed to the vehicle as required.
  • Clear the code and road test to confirm the fault does not return.

Can I keep driving?

Medium severity

The car can usually be driven carefully a short distance to a workshop, but a cylinder that is not firing can send unburnt fuel into the catalytic converter and cause damage. Avoid heavy loads and long journeys, and stop if the engine runs very roughly or the warning light flashes.

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

This code for other makes

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