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DTC codes / Ford codes / P1272

P1272 · FordCylinder 2 High To Low Side Open

P1272 on Ford vehicles means the powertrain control module (PCM) has detected an open circuit between the high and low sides of the fuel injector for cylinder 2. The PCM monitors injector circuit continuity and flags this code when the expected current path is broken, typically due to a wiring fault or failed injector.

SystemPowertrain
Code typeFord specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Often no symptoms besides the warning light, especially if the engine runs smoothly at idle and light load
  • Rough idle or misfire that may be more noticeable when the engine is cold
  • Hesitation or stumble during acceleration
  • Reduced engine power or poor fuel economy
  • A flashing check engine light in severe cases indicating a misfire that could damage the catalytic converter

Common causes, most likely first

  1. Open or damaged wiring in the injector harness between the PCM and cylinder 2 injector
  2. Failed cylinder 2 fuel injector with an open internal coil
  3. Corroded or loose electrical connector at the cylinder 2 injector
  4. Chafed or broken wire in the main engine harness, often near sharp edges or heat sources
  5. Faulty PCM driver for the cylinder 2 injector circuit (rare but possible)
  6. Aftermarket alarm or remote start wiring that has compromised the injector circuit

How to diagnose and fix it

  1. Inspect the cylinder 2 injector connector for corrosion, loose pins, or damaged terminals and clean or repair as needed
  2. Check the injector harness for continuity and resistance between the PCM connector and the injector connector, looking for opens or shorts
  3. Measure the resistance of the cylinder 2 injector and compare it to the manufacturer's specification; replace if out of range
  4. Perform a wiggle test on the harness while monitoring injector circuit continuity to reveal intermittent opens
  5. Check for technical service bulletins (TSBs) or wiring concerns specific to the vehicle model and engine
  6. If wiring and injector are good, test the PCM driver circuit with a noid light or oscilloscope to confirm PCM operation
  7. Replace the PCM only after all other possibilities are ruled out and reprogramming is required

Before you replace the cylinder 2 injector

  • A common misdiagnosis is replacing the injector when the real fault is a chafed wire in the harness near the intake manifold or valve cover, so always perform a continuity test before condemning the injector.
  • The code can set intermittently due to a loose connector that only loses contact when the engine moves under torque, so a wiggle test while watching live data is essential.
  • On some Ford engines, the injector harness is part of the main engine harness and a single broken wire can affect multiple injectors, so check for other codes like P1271 or P1273.
  • A failed injector coil can sometimes test good when cold but open when hot, so resistance checks should be done both cold and after warming the engine.
  • Aftermarket electrical accessories tapped into the injector wiring can introduce resistance or opens that trigger this code, so inspect for non-factory wiring before assuming a factory defect.

Can I keep driving with P1272?

You can drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing because a misfiring cylinder can overheat the catalytic converter. If the check engine light is flashing, stop driving and have the vehicle towed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Ford vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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