P1277: Cylinder #7 Injector Circuit Open (High to Low Side)
The P1277 code indicates an open circuit between the high and low sides of the fuel injector for cylinder #7. This typically means the injector coil has failed (open winding) or there is a wiring/connector issue in the injector circuit. The ECM detects a lack of electrical continuity, preventing the injector from firing, which causes a misfire and potential engine performance issues.
01. Most Common Causes
- Faulty fuel injector (open coil) on cylinder #7
- Open or shorted wiring in the injector circuit
- Corroded or damaged connector at the injector
- ECM internal failure (rare)
02. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire on cylinder #7
- Rough idle, hesitation, or loss of power
- Increased fuel consumption and possible catalytic converter damage
03. Step-by-Step Diagnosis
Step 1: Scan for codes and confirm P1277. Check freeze frame data.
Step 2: Visually inspect injector #7 connector and wiring for damage or corrosion.
Step 3: Measure resistance across injector #7 terminals (should be 11-18 ohms). If open, replace injector.
Step 4: Check for 12V power and ground signal at injector connector with key on. If missing, trace wiring back to ECM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with a misfire can damage the catalytic converter and cause poor performance. It's best to repair promptly.
How much does it cost to fix?▼
Typically $50-$150 for a DIY injector replacement, or $200-$400 at a shop including labor.