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P0270 — Cylinder 4 Injector Circuit Low

Generic OBD-II · all makesPowertrain (engine & transmission)

The code indicates that the electrical circuit for the fourth cylinder’s fuel injector is receiving insufficient voltage or current.

Symptoms

What causes it — most likely first

1. Faulty injector

The injector may have an internal short or open that draws too little current, causing the circuit to register low.

2. Wiring or connector problem

Damaged, corroded, or loose wiring harness or connector can restrict current flow to the injector.

3. PCM injector driver circuit issue

A failure in the PCM’s driver circuit for cylinder 4 can reduce voltage supplied to the injector.

4. Injector driver module failure (if separate)

Some vehicles use a separate driver module that can fail, affecting only that cylinder’s injector circuit.

How it's diagnosed

  1. Inspect the injector and its wiring harness for visible damage or corrosion.
  2. Check the connector pins for proper seating and clean contacts.
  3. Measure injector resistance and compare to manufacturer specifications.
  4. Test injector voltage during cranking or while the engine is running.
  5. Swap the injector with one from another cylinder to see if the fault follows the injector.
  6. If all hardware checks are clear, verify PCM driver output using a scan tool or oscilloscope.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0268 — Cylinder 3 Injector Circuit HighP0269 — Cylinder 3 ContributionbalanceP0271 — Cylinder 4 Injector Circuit HighP0272 — Cylinder 4 ContributionbalanceP0273 — Cylinder 5 Injector Circuit LowP0274 — Cylinder 5 Injector Circuit High

Frequently asked

Will replacing the PCM fix P0270?

No. The PCM is rarely the cause; most often the problem is the injector, its wiring, or a connector.

Can a low fuel pressure cause this code?

Low fuel pressure usually triggers different codes; it does not directly cause a low‑circuit reading on a specific injector.

Is it safe to drive with this code?

Driving with a misfire can lead to reduced performance and increased emissions; it is best to address the issue promptly.

Do I need to replace the entire injector?

Only replace the injector if testing confirms it is defective; many times the issue is resolved by repairing wiring or the connector.