P2B18 means injector 5 has no learned offset. No manufacturer documents this exact code. On petrol direct injection GM covers a related idea with codes of its own: in the 2025 V8 table the ECM adds up the opening magnitude and closing time compensation of each injector, both derived from the feedback voltage, and P10AB or P10AC set for cylinder 5 when that sum is below the minimum or above the maximum limit (Type B, 50 to 100 samples). A not-learned status, by contrast, says that no usable value exists yet, for example after a new injector or control unit or after an adaption reset. For diesel engines CARB (f)(4.2.4)(A)(i) requires detection of feedback that does not start in time. The limit-exceeded twin is P2B19.
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 5 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Warning lamp
- Rarely noticeable; at most slightly uneven low-load running
Most likely causes
- New injector 5 or control unit without a completed learn
- Enabling conditions for the learn not met often enough
- Faulty injector 5 wiring preventing a valid measurement
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 P2B18 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 18: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B18?
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 P2B18?
The most common causes are: new injector 5 or control unit without a completed learn; enabling conditions for the learn not met often enough; faulty injector 5 wiring preventing a valid measurement.
Related codes
- P2B19Cylinder 5 Injection Pulse Offset Exceeded Learning Limit
- P2B16Cylinder 4 Injection Pulse Offset Not Learned
- P2B1ACylinder 6 Injection Pulse Offset Not Learned
- P2B04Cylinder 5 Injection Pulse Performance
- P02D4Cylinder 5 Fuel Injector A Offset Learning At Min Limit
- P02D5Cylinder 5 Fuel Injector A Offset Learning At Max Limit
- P0275Cylinder 5 Contribution/Balance
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.