P0263 — Cylinder 1 Contribution/Balance Fault — 6.7 Cummins (SCR / DEF)
Diagnostic reference for 6.7L Cummins SCR/DEF 2013–present.
What it means
The PCM detects that cylinder 1 output deviates from the others (Pxx6x family covers cylinders 1-8).1
Most likely causes
- Cylinder 1 injector performance / balance issue — Solenoid injector for cylinder 1 delivering uneven fuel quantity vs other cylinders; PCM flags contribution/balance fault. Typical on this platform: 6.7L Cummins 2013–present (SCR/DEF).1
- Injector electrical circuit fault for cylinder 1 — Engine control module detects electrical fault in fuel injector circuit for cylinder number one.2
How to diagnose
- Verify code P0263 present and check for accompanying injector circuit codes such as P0201 for cylinder 1.
- Review freeze-frame data for engine speed, load, rail pressure, and fuel temperature at time of set.
- Perform cylinder contribution/balance test using scan tool to confirm cylinder 1 deviation.
- Inspect injector electrical connector and harness for damage, corrosion, or loose pins at cylinder 1.
- Check injector driver circuit integrity and ECM injector control signals for cylinder 1.
- Compare rail pressure actual vs desired during idle and load; note platform uses Bosch CP3 for 2013–2018 and 2021+, CP4.2 for 2019–2020 only.
- Assess low-pressure supply from factory in-tank electric supply pump / fuel module for adequate volume and pressure.
- Inspect common-rail solenoid injectors condition; P0201–P0206, P0263-family apply to this platform.
Parts and tools you may need
- Scan tool with Cummins enhanced diagnostics and cylinder contribution test
- Digital multimeter
- Oscilloscope for injector command signal
- Fuel pressure test gauge for low-pressure supply
- Service information for injector circuit schematics
Tools you’ll need
- OBD-II scan tool — Reads P0263 and related injector codes, provides freeze-frame data and runs cylinder contribution/balance tests to confirm cylinder 1 deviation.
- digital multimeter — Checks injector electrical connector continuity, resistance, and ECM driver signals for cylinder 1 faults.
- fuel pressure gauge — Verifies low-pressure supply volume/pressure and compares rail pressure actual vs desired during idle and load.
- oscilloscope — Captures injector solenoid control waveforms to identify electrical circuit faults or driver anomalies for cylinder 1.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Wiring or connector repair | $10–$100 | 1–4 hrs | DIY with tools and a manual |
| Fuel injector (each) | $350–$700 | 1–2 hrs | Shop |
Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.
When to see a pro
If diagnosis indicates internal injector failure, high-pressure fuel system concern, or ECM driver fault, have a qualified diesel technician evaluate. Do not attempt step-by-step repair of high-pressure fuel components.
Check for recalls
Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.
Sources
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