Cylinder 4 Injector Circuit Low
The P0270 code indicates that the Engine Control Module (ECM) has detected a low voltage or resistance condition in the electrical circuit of the fuel injector for cylinder 4. This typically means the injector circuit is drawing less current than expected, often due to a short to ground, open circuit, or a faulty injector. The ECM monitors the injector driver circuit and sets this code when the voltage is below a calibrated threshold during the injector pulse.
01. Most Common Causes
- Faulty fuel injector on cylinder 4 (internal short or open)
- Open or shorted wiring in the injector circuit (harness damage, corrosion)
- Poor electrical connection at the injector or ECM connector
- Failed ECM (rare)
02. Symptoms You Will Notice
- Engine misfire on cylinder 4
- Rough idle or hesitation during acceleration
- Check Engine Light illuminated
- Possible fuel odor or decreased fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data. Clear code and test drive to confirm reoccurrence.
Step 2: Visually inspect the injector wiring harness and connector for cylinder 4 for damage, corrosion, or loose pins.
Step 3: Measure resistance of cylinder 4 injector with a multimeter (typically 11-18 ohms). Compare to other injectors.
Step 4: Check for voltage at the injector connector with key on (should see battery voltage on one pin).
Step 5: Use a noid light or oscilloscope to test injector pulse while cranking. If no pulse, check wiring back to ECM.
Step 6: If all tests pass, suspect a faulty ECM (rare). Perform ECM relay and ground checks.
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?▼
Costs vary: injector replacement $150-$400, wiring repair $100-$300, ECM replacement $500-$1000. Diagnosis fee typically $100-$150.