P0263

Cylinder 1 Contribution/Balance

Fuel injector / cylinder balance Generic OBD-II High

What it means

P0263 means the ECM has determined that cylinder 1 is producing less power than the other cylinders — its "contribution" to running the engine is out of balance. This usually points to a weak or clogged injector, low fuel delivery, or low compression on cylinder 1, and it shows up as rough running, misfire, and reduced power.

High

Can I keep driving? Limited — cylinder 1 is contributing less than the others, so the engine runs rough and down on power; drive gently until it's fixed.

Real-world scan data

Seen in

1,131

scans in the past year

Found in

0.2%

of scans

0.3%

of scans that found faults

Appears alongside · share of P0263 scans

P0269in 71.0% of scans

P0266in 69.4% of scans

P0272in 67.5% 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, misfire, or engine shaking
Reduced power and hesitation on acceleration
Occasional stalling at idle

Common causes

Most likely first

Weak, clogged, or leaking fuel injector on cylinder 1 (most common)Likely
Low compression in cylinder 1 (valve or ring wear)Common
Low fuel pressure or a fuel-delivery restriction to that cylinderCommon
Wiring or connector fault at the cylinder 1 injectorLess often
Faulty ECM (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and run an injector balance/contribution test to confirm cylinder 1 is weak.
Check fuel pressure and inspect the cylinder 1 injector for clogging or leakage.
Inspect the injector's wiring and connector.
Run a compression test on cylinder 1 to rule out a mechanical cause.
Clean or replace the injector as needed; address compression issues if found. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0263?+

Only briefly. A cylinder that isn't pulling its weight causes misfires that can overheat the catalytic converter, so get it diagnosed soon.

Can I just clear P0263?+

It comes back until the weak injector, fuel-delivery issue, or compression problem on cylinder 1 is repaired.

Read & clear P0263 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