P2B05 marks missed injection pulses on cylinder 6 outside the cold-start window; on a six-cylinder engine this is the last cylinder in the order of numbers. No manufacturer documents P2B05 publicly as a stand-alone check. GM's 2025 V8 calibration (25OBDG06A/06B) lists it only in the support tables shared by the pulse family. One of them shows why the check is tied to split injection: double or triple pulses are allowed only up to about 3,000–3,600 rpm, depending on mode and injector energy profile, and per GM's 2018 definitions single-pulse data are evaluated below 5,000 rpm. A fault therefore tends to show at low and medium speed. The injector of cylinder 6 is first suspect, wiring second; the cold-start counterpart is P2B0D.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Cylinder 6 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Check engine light
- Slight shaking at idle or low speed, misfire on cylinder 6 (P0306)
Most likely causes
- Deposits or wear on the cylinder 6 injector hampering small pulses
- Contact problem at the injector 6 plug
- Injector driver or voltage sensing in the ECM faulty
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P2B05 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 05: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B05?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P2B05?
The most common causes are: deposits or wear on the cylinder 6 injector hampering small pulses; contact problem at the injector 6 plug; injector driver or voltage sensing in the ECM faulty.
Related codes
- P2B0DCold Start Cylinder 6 Injection Pulse Performance
- P2B04Cylinder 5 Injection Pulse Performance
- P2B06Cylinder 7 Injection Pulse Performance
- P2B96Injection Pulse Performance
- P02F3Cylinder 6 Injector Circuit Range/Performance
- P0206Cylinder 6 Injector A Circuit/Open
- P0306Cylinder 6 Misfire Detected
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.