P1274: Cylinder #4 Injector Circuit Open (High to Low Side)
The P1274 code indicates an open circuit between the high and low sides of the fuel injector for cylinder #4. This typically means the injector coil has failed (open winding) or there is a wiring issue (broken wire, poor connector) in the injector circuit. The ECM monitors the injector driver circuit and detects when the current flow is interrupted, setting this code. This can cause a misfire, rough idle, and increased emissions.
01. Most Common Causes
- Faulty fuel injector (open coil) on cylinder #4
- Open or shorted wiring in injector circuit
- Damaged connector at injector or ECM
- ECM internal driver failure (rare)
02. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire (especially at idle or under load)
- Rough idle or hesitation
- Reduced fuel economy and power
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect injector #4 connector and wiring for damage or corrosion.
Step 3: Measure resistance of injector #4 (should be 11-18 ohms; open indicates faulty injector).
Step 4: Check for 12V power and ground signal at injector connector with key on engine off.
Step 5: If wiring and injector are good, test ECM output with a noid light or lab scope.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a misfire can damage the catalytic converter and cause poor performance. Have it diagnosed promptly.
How much does it cost to fix?▼
Replacing a single injector typically costs $150-$400 including parts and labor. If wiring repair is needed, cost may be lower.