P1261 - High to Low Side Short in Cylinder #1 Injector Circuit
The P1261 code indicates a short circuit between the high and low sides of the fuel injector circuit for cylinder #1. This typically occurs when the injector's internal winding fails or the wiring harness is damaged, causing a direct electrical connection between the injector's power and ground circuits. This can lead to injector malfunction, misfires, and potential damage to the engine control module (ECM) if not addressed promptly.
01. Most Common Causes
- Faulty fuel injector on cylinder #1 (internal short)
- Damaged wiring or connector for injector #1 (chafed, melted, or pinched wires)
- Corrosion or moisture in the injector connector
- ECM internal failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire on cylinder #1
- Rough idle or hesitation during acceleration
- Decreased fuel economy and power loss
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm code P1261 and check for related codes (e.g., misfire codes).
Step 2: Visually inspect the wiring and connector for injector #1 for damage, corrosion, or loose connections.
Step 3: Measure resistance between the high and low side pins of injector #1; a short (near 0 ohms) indicates a faulty injector.
Step 4: If wiring and injector appear okay, test the ECM output for injector #1 using a multimeter or oscilloscope.
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, reduced performance, and potential damage to the ECM or catalytic converter.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including parts (injector ~$50-$150) and labor (1-2 hours at $100-$150/hour).