P0270
Cylinder 4 Injector A Circuit Low
Injector circuit
Generic OBD-II
High
What it means
P0270 means the ECM detects an abnormally low signal on the cylinder 4 injector control circuit. If that injector isn't firing properly, cylinder 4 misfires — causing a rough idle, reduced power, and, over time, possible catalytic-converter damage until the wiring or injector is repaired.
High
Can I keep driving? Usually driveable, but cylinder 4 may misfire and run rough; sustained misfiring can overheat the catalytic converter, so fix it soon.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or a misfire on cylinder 4
- Reduced power and hesitation
- Possible dead cylinder and increased fuel use
Common causes
Most likely first
- Damaged wiring or a corroded connector at the cylinder 4 injectorLikely
- Faulty cylinder 4 fuel injector (open or shorted winding)Common
- Poor ground or open in the injector control circuitCommon
- PCM injector-driver fault (less common)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the cylinder 4 injector connector and wiring.
- Measure the injector's resistance and compare it to the other injectors.
- Check the injector control-circuit voltage and ground from the connector.
- Replace the injector if it's out of spec; consider the PCM driver only after wiring is confirmed good. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0270?+
Short-term yes, but a dead or misfiring cylinder makes the engine run rough and can damage the catalytic converter over time. Repair it soon.
Can I just clear P0270?+
It returns until the injector or its wiring is fixed. A 'circuit low' code reflects a real electrical fault on that injector.
Related codes
Often seen with P0270
Read & clear P0270 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX