P0271 Code: Cylinder 4 Injector Circuit High
🟠 Moderate severity · drivable
Drivable, but cylinder 4 may not fire, causing a rough idle or misfire. Fix it soon.
What P0271 means
The engine computer monitors the electrical circuit that fires the fuel injector for cylinder 4. This code means the voltage in that circuit is higher than expected, so the computer may not be able to control the injector properly and fuel delivery to cylinder 4 may stop.
Symptoms
- Check engine light is on (may flash)
- Rough idle or misfire on cylinder 4
- Loss of power
- Poor fuel economy
Common causes
- most common: Damaged injector wiring shorting to power
- common: Faulty fuel injector on cylinder 4 (failed coil)
- common: Loose, corroded, or water-damaged connector
- less common: Injector driver fault in the engine computer
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect, clean, and reseat the cylinder 4 injector connector | Yes | $0–20 |
| Test the injector resistance with a multimeter | Yes | $0–30 |
| Repair wiring that is shorted to power | Mechanic | $50–200 |
| Replace the cylinder 4 fuel injector | Mechanic | $150–600 |
Frequently asked questions
Can I drive with a P0271 code?
Yes, but cylinder 4 may not fire, causing rough running and a possible misfire. Drive only short distances and fix it soon to protect the catalytic converter.
What is the most common cause of P0271?
Injector wiring that is shorted to power, or a failed fuel injector on cylinder 4.
How much does it cost to fix a P0271?
Usually $150–$600 for a new injector. A simple wiring or connector repair can cost much less.
Related codes
P0270
P0270 Code: Cylinder 4 Injector Circuit Low
P0272P0272 Code: Cylinder 4 Not Contributing Enough Power (Contribution/Balance)
P0304P0304 Code: Cylinder 4 Misfire Detected
Related guide: The 10 Most Common Check Engine Codes →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.