P0271

Cylinder 4 Injector A Circuit High

Q: Is it safe to drive with P0271?

Only briefly. A dead or misfiring cylinder loads unburnt fuel into the exhaust, which can overheat and damage the catalytic converter.

Q: Can I just clear P0271?

It returns quickly because the injector circuit fault is still present. The wiring or injector must be repaired.

Fuel injector circuit Generic OBD-II High

What it means

P0271 means the control module detects an abnormally high voltage on the cylinder-4 injector control circuit — typically a short to voltage or an injector fault. When the injector can't be driven correctly, cylinder 4 misfires, so the engine runs rough and loses power. A sustained misfire can also damage the catalytic converter, so it's worth prompt attention.

High

Can I keep driving? Cylinder 4 may drop out and misfire, so the engine runs rough and down on power; drivable short distances, but a persistent misfire can harm the catalytic converter.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Rough idle or a misfire from cylinder 4
Reduced power and hesitation
Increased fuel consumption or a fuel smell

Common causes

Most likely first

Short to voltage in the cylinder-4 injector control wiringLikely
Faulty injector for cylinder 4Common
Corroded or loose connector at the injectorCommon
Failed injector driver in the PCM (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the fault is on the cylinder-4 injector circuit.
Inspect the injector connector and wiring for a short to voltage, chafing, or corrosion.
Measure the injector's resistance and compare it to the other injectors.
Swap the suspect injector with a known-good cylinder to see if the fault follows it.
Replace the injector or repair the wiring as indicated; consider the PCM driver only last. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0271?+

Only briefly. A dead or misfiring cylinder loads unburnt fuel into the exhaust, which can overheat and damage the catalytic converter.

Can I just clear P0271?+

It returns quickly because the injector circuit fault is still present. The wiring or injector must be repaired.

Read & clear P0271 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX