P1269

Cylinder #4 High To Low Side Short

Powertrain Fuel and Air Metering Fuel Injector Circuit 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

Cylinder #4's fuel injector circuit has a short between its high and low voltage sides, similar to a wire touching where it shouldn't in an electrical cord. This prevents the injector from opening properly, causing that cylinder to misfire.

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Symptoms You May Notice

3 known symptoms for this code
Engine misfire or rough idle, especially at cylinder #4
Check Engine Light illuminated
Possible loss of power and poor fuel economy
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECM monitors the voltage and current flow through cylinder #4's fuel injector driver circuit. It detects abnormal resistance or voltage drops that indicate a short between the high-side and low-side control signals. When resistance falls below threshold, the fault is triggered.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Injector Circuit Resistance 0.8–1.5 ohms per coil < 0.5 ohms or shorted path detected
Injector Voltage Drop 10–14V during pulse Collapsed or zero differential voltage
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Fuel injector electrical connector (cylinder #4)
Inspect and reseat the connector; clean any corrosion or moisture from pins.
2
Fuel injector wiring harness (cylinder #4)
Check for pinched, melted, or damaged insulation between injector and ECM; repair or replace compromised sections.
3
Fuel injector (cylinder #4)
Replace the injector if internal coil windings are shorted or failed.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P1269 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P1269

What happens after you fix the fault

Once the fault is repaired, P1269 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.