What Does P1265 Mean?
The ECM has detected a high-to-low side short circuit in the cylinder #5 fuel injector driver circuit. This code is specific to engines with five or more cylinders (V6, V8, V10, or inline-5 configurations). The short between the injector's power and control circuits prevents proper fuel metering for cylinder #5, causing a misfire on that cylinder.
Safety Warning
Persistent cylinder #5 misfire reduces engine power and causes rough running. Unburned fuel contaminates the catalytic converter and can cause overheating or failure. The shorted circuit risks damaging the ECM driver, which would be a costly secondary failure.
Common Causes
35%
Harness damage near the cylinder #5 injector with high and low side wires making contact
30%
Internal short circuit in the cylinder #5 fuel injector
20%
Corrosion or contamination in the cylinder #5 injector connector
15%
ECM driver circuit failure for the cylinder #5 injector output
Diagnostic Steps
1
Scan for related misfire code P0305 and other injector driver codes to determine if the issue affects only cylinder #5.
2
Locate cylinder #5 on your engine configuration and disconnect the injector connector. Inspect for signs of heat damage, corrosion, or cross-contamination between terminals.
3
Measure the injector coil resistance and compare to specifications. Check for any short between the injector terminals and the injector body.
4
Test the harness wires at the connector for continuity between each other with the injector disconnected — no continuity should exist.
5
Swap the cylinder #5 injector with a neighboring cylinder, clear codes, and retest to isolate whether the fault is the injector or the wiring.
Estimated Repair Cost
$100 - $550
Parts + labor, varies by vehicle and location
The ECM has detected a high-to-low side short circuit in the cylinder #5 fuel injector driver circuit. This code is specific to engines with five or more cylinders (V6, V8, V10, or inline-5 configurations). The short between the injector's power and control circuits prevents proper fuel metering for...
The most common cause of P1265 (Cylinder #5 High To Low Side Short) is: Harness damage near the cylinder #5 injector with high and low side wires making contact
Typical repair costs for P1265 range from $100 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Persistent cylinder #5 misfire reduces engine power and causes rough running. Unburned fuel contaminates the catalytic converter and can cause overheating or failure. The shorted circuit risks damaging the ECM driver, which would be a costly secondary failure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1265 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Manufacturer
Recommended Tools
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