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P1237

Injector Circuit Cylinder 6 Intermittent.

  • Chevrolet
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
2
AreaFuel and air metering (injector circuit)
37
FaultThe specific fault in that area

What it means

P1237 on a Chevrolet means the engine control module has detected an intermittent fault in the fuel injector circuit for cylinder 6. The module monitors the injector driver and its wiring, and it saw a signal that came and went, such as an open circuit, a short or an unstable voltage, rather than a constant failure. Because the fault is intermittent, it may only appear when the engine is hot, vibrating or under load.

Symptoms

  • Engine misfire or rough running on cylinder 6, often intermittent
  • Malfunction indicator lamp on
  • Hesitation or loss of power under acceleration
  • Rough idle or occasional stumble
  • Poor fuel economy
  • Occasional hard starting or the engine cutting out briefly

Possible causes

  • Intermittent wiring fault in the cylinder 6 injector feed or control wire (chafing, broken strands, rubbing on the engine)likely
  • Corroded, loose or damaged connector terminals at the cylinder 6 injectorlikely
  • Injector with an intermittently failing internal coil or incorrect winding resistancelikely
  • Poor connection at the engine control module connector or a related harness jointpossible
  • Intermittent loss of the injector power supply or a poor earth shared by the injector circuitpossible
  • Faulty injector driver inside the engine control modulerare

How to diagnose

  1. Read all stored and pending codes and record the freeze frame data (engine temperature, load, speed) to see when the fault occurs
  2. Check for related misfire codes for cylinder 6 and any other injector circuit codes that might point to a shared fault
  3. Visually inspect the cylinder 6 injector connector and harness for chafing, heat damage, corrosion, bent or pushed-back terminals
  4. With the engine running, gently wiggle the harness and connector at the injector while watching for a change in idle quality or live misfire data
  5. Measure the cylinder 6 injector coil resistance and compare it with the specification for your engine, which varies by model
  6. Check the injector power supply and earth for voltage drop, and test the control wire for continuity and shorts to earth or voltage
  7. Use a suitable noid light or oscilloscope to confirm the injector pulse is steady while the engine is running
  8. Inspect the engine control module connector pins for corrosion or looseness, and check for any applicable software updates for your model

How to fix

  • Repair or replace the damaged section of wiring, using proper soldered or sealed joints
  • Clean or replace the corroded or damaged injector connector and terminals
  • Replace the cylinder 6 injector if its resistance or pulse pattern is out of specification
  • Repair the injector power supply or earth connection if voltage drop is found
  • Repair the engine control module connector terminals, and only consider replacing or reprogramming the module if testing proves it is faulty or an outdated calibration is a known cause for that model

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but an injector that cuts out can cause misfires and unburnt fuel reaching the catalytic converter, so get it checked soon. 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.

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