P0270 means Cylinder 4 Injector Circuit Low. The cylinder 4 injector circuit voltage is lower than expected, usually from a short to ground on the control side. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0270 means
Each fuel injector is a small solenoid that the engine computer switches on and off many times a second. The computer monitors every injector circuit for opens and shorts, and an injector circuit fault usually comes with a misfire on the same cylinder because that cylinder gets no fuel.
P0270 symptoms
- Misfire on cylinder 4, often with P0304
- Rough idle and shaking
- Loss of power
- Check engine light, possibly flashing
Common causes of P0270
- Wiring shorted to ground
- Shorted injector coil
- Damaged connector
- Fault in the computer’s injector driver (less common)
How to diagnose P0270
- Inspect the harness for chafing
- Measure injector resistance
- Check the circuit for shorts with the connector unplugged
- Swap the injector with a neighboring cylinder and see whether the code follows it
- Clear the code and confirm misfire counts stay at zero on a test drive
Can you drive with P0270?
Only briefly; a dead cylinder can overheat the catalytic converter, and a leaking injector can wash fuel into the oil.
P0270 tips
Look for a chafed injector harness where it crosses brackets or the intake; a short to ground pulls the circuit low.
Will P0270 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0270 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0204 | Injector Circuit/Open – Cylinder 4 |
| P0304 | Cylinder 4 Misfire Detected |
| P0271 | Cylinder 4 Injector Circuit High |
Guides that help
When it is more than a sensor
If an injector and its wiring test good but the cylinder still misfires, a compression test separates a fuel problem from a mechanical one; see engine replacement cost and our engines page if the engine is worn.
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