P0270 Code: Cylinder 4 Injector Circuit Low
🟠 Moderate severity · drivable
Drivable, but cylinder 4 may not fire, causing a rough idle or misfire. Fix it soon.
What P0270 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 lower than expected, so the computer may not be able to open the injector and deliver fuel to cylinder 4.
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: Faulty fuel injector on cylinder 4 (worn coil)
- common: Damaged wiring or a loose connector at the injector
- common: Short to ground in the injector wiring
- less common: Corroded or water-damaged injector connector
- rare: 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 damaged or shorted injector wiring | Mechanic | $50–200 |
| Replace the cylinder 4 fuel injector | Mechanic | $150–600 |
Frequently asked questions
Can I drive with a P0270 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 P0270?
A failed fuel injector on cylinder 4, or a wiring and connector problem in that injector's circuit.
How much does it cost to fix a P0270?
Usually $150–$600 for a new injector. A simple wiring or connector repair can cost much less.
Related codes
P0271
P0271 Code: Cylinder 4 Injector Circuit High
P0272P0272 Code: Cylinder 4 Not Contributing Enough Power (Contribution/Balance)
P0304P0304 Code: Cylinder 4 Misfire Detected
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.