Cylinder #3 High to Low Side Short in Fuel Injector Circuit
Code P1263 indicates a short circuit between the high and low sides of the fuel injector driver circuit for cylinder #3. This typically means the injector coil has failed internally, creating a direct electrical path between the battery voltage (high side) and the ground control (low side) circuits. This can cause the injector to malfunction, leading to misfires, poor fuel economy, and potential damage to the engine control module (ECM) if not addressed promptly.
01. Most Common Causes
- Faulty fuel injector on cylinder #3 (internal short)
- Wiring harness damage or short between injector wires
- Corroded or damaged connector at injector #3
- ECM internal failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire on cylinder #3
- Rough idle or hesitation during acceleration
- Decreased fuel economy
- Possible engine stalling
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect injector #3 connector and wiring for damage or corrosion.
Step 3: Measure resistance of injector #3; compare to specification (typically 11-17 ohms).
Step 4: Perform a continuity test between injector high and low side wires; a short indicates a problem.
Step 5: Swap injector #3 with another cylinder and see if the code follows; if yes, replace injector.
Step 6: If wiring is suspect, repair or replace harness section.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a shorted injector can cause misfires, poor performance, and may damage the ECM or catalytic converter. Have it diagnosed and repaired as soon as possible.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including parts and labor. A single fuel injector replacement is around $50-$150 for the part, plus 1-2 hours of labor at $100-$150 per hour.