P0203

Cylinder 3 Injector A Circuit

Fuel injector circuit Generic OBD-II High

What it means

P0203 means the ECM has detected an electrical fault in the fuel injector circuit for cylinder 3. If the circuit is open or shorted, that injector may stop firing, so cylinder 3 misfires and the engine runs rough with reduced power. The most common causes are damaged wiring, a bad connector, or a failed injector solenoid on that cylinder.

High

Can I keep driving? Limited — if the injector circuit is dead, cylinder 3 won't fire and the engine runs rough and down on power; drive as little as possible.

Real-world scan data

Seen in

6,514

scans in the past year

Found in

1.0%

of scans

1.8%

of scans that found faults

Appears alongside · share of P0203 scans

P0202in 70.0% of scans

P0201in 69.7% of scans

P0204in 50.9% of scans

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 and noticeable misfire on cylinder 3
Reduced power and hesitation
Possible fuel smell or raw fuel in the exhaust

Common causes

Most likely first

Damaged wiring or a connector open/short on the cylinder 3 injector circuit (most common)Likely
Failed injector solenoid on cylinder 3Common
Corroded or loose connector at the injectorCommon
Faulty injector driver in the ECM (rare)Less often

How to diagnose & fix

Work through it in order

Inspect the injector's connector and wiring for damage, corrosion, or an open circuit.
Measure the injector's coil resistance and compare it to the other injectors.
Check that the injector is receiving a pulse from the ECM (noid light or scope).
Swap the injector with an adjacent cylinder to see if the fault follows it.
Replace the injector if it's failed; repair wiring or consider the ECM driver last. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0203?+

Not for long. A dead injector means one cylinder isn't firing, which runs raw fuel into the exhaust and can damage the catalytic converter.

Can I just clear P0203?+

It returns as soon as the ECM sees the circuit fault again. The wiring, connector, or injector has to be repaired first.

Read & clear P0203 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