Cylinder 4 Injector Circuit High
What does P0271 mean?
The P0271 code means the vehicle's onboard diagnostic system has detected: Cylinder 4 Injector Circuit High. This is a moderate severity code.
Common Symptoms
- Engine misfire on cylinder 4
- Rough idle and vibration
- Check Engine Light illuminated
- Dead cylinder 4
- Poor fuel economy
Probable Causes (Ranked by Likelihood)
- Open circuit in cylinder 4 injector wiring Very High
- Faulty cylinder 4 fuel injector (open coil) High
- Disconnected or corroded injector connector High
- Broken ground wire to injector Moderate
- PCM injector driver circuit failure Low
Step-by-Step Diagnostic Procedure
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Measure cylinder 4 injector resistance -- an open reading (OL) confirms a burnt-out coil
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Check for 12V power at the injector connector with key on
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Test for PCM ground pulse at the connector using a noid light during cranking
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Inspect the connector for pushed-back pins, corrosion, or water intrusion
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Replace injector if coil is open; repair wiring if a break is found in the circuit
Frequently Asked Questions
Can I drive with code P0271?
You can drive short distances. Cylinder 4 will not fire, causing noticeable vibration and power loss. Repair promptly to protect the catalytic converter.
What is the most common cause of P0271?
The most common cause is an open circuit, either from a burnt-out injector coil or a broken wire. Corroded connectors are also frequent culprits, especially in areas with road salt.
How do I test an injector coil?
Set a multimeter to the ohms setting and measure across the two injector terminals. A good injector typically reads 11-18 ohms. An open reading (OL) means the coil is burnt out.