P1269: Cylinder 4 Injector Circuit Short
The P1269 code indicates a short circuit between the high side and low side of the cylinder #4 injector circuit. In Ford fuel injection systems, each injector is controlled by a two-stage driver: the high side supplies battery voltage, and the low side controls ground through a transistor inside the PCM. This code sets when the PCM detects abnormal electrical continuity between the two sides of the injector circuit, preventing proper fuel delivery to that cylinder. The condition may be intermittent or permanent and is typically detected during injector driver self-tests.
01. Most Common Causes
- Short circuit between high-side and low-side wires in the cylinder #4 injector circuit
- Internally shorted fuel injector on cylinder #4
- Damaged, corroded, or bent pins in the injector connector or harness
- Internal PCM failure in the cylinder #4 injector driver
- Moisture or contamination in the injector connector causing current leakage
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire on cylinder #4
- Rough idle or poor acceleration
- Decreased fuel economy
- Possible hard starting or no-start condition
03. Step-by-Step Diagnosis
Scan for codes and record freeze frame data
Visually inspect the cylinder #4 injector connector and wiring for damage, corrosion, or shorts
Measure resistance between the high-side and low-side circuits at the injector connector; compare to specifications (typically 10-18 ohms for the injector itself, but a short will show near zero)
Perform a wiggle test on the harness while monitoring the circuit with a multimeter or oscilloscope
Swap the injector with another cylinder to see if the code follows; if so, replace the injector
If wiring and injector are good, test the PCM output; if no output, suspect PCM failure
1. Frequently Asked Questions
Is it safe to drive?▼
No, it is not recommended. Driving with a shorted injector circuit can cause misfire, reduced performance, and potential damage to the PCM or catalytic converter. Have the vehicle diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $150 to $600, depending on the cause. A simple injector replacement may cost $150-$300, while PCM replacement can exceed $500-$1000 including programming.