P2B1C says no learned offset exists for injector 7, which only applies to engines with at least seven cylinders, in practice V8s. No manufacturer publishes a monitor for this code. A GM patent on small-quantity adaption shows that a learn can also fail to finish because results do not settle: several test injections during fuel cut-off are compared, and an injector whose consecutive values scatter too much gets a low confidence rating and is marked suspicious instead of passing. A noisy speed signal, an injector with erratic opening or a leak in the high-pressure system can therefore block a valid value. Bosch's zero-fuel calibration patent rests on the same speed-based detection. CARB (f)(4.2.4)(A)(i) asks for missing learning to be flagged; P2B1D is the out-of-range sibling.
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 7 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Warning lamp
- With an erratic injector, uneven idle or knocking on one cylinder
Most likely causes
- Test results for injector 7 scattering too much to be accepted
- Learn restarted after injector or control unit replacement
- Leak in the high-pressure system disturbing the test injection
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 P2B1C means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 1C: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B1C?
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 P2B1C?
The most common causes are: test results for injector 7 scattering too much to be accepted; learn restarted after injector or control unit replacement; leak in the high-pressure system disturbing the test injection.
Related codes
- P2B1DCylinder 7 Injection Pulse Offset Exceeded Learning Limit
- P2B1ACylinder 6 Injection Pulse Offset Not Learned
- P2B1ECylinder 8 Injection Pulse Offset Not Learned
- P02D8Cylinder 7 Fuel Injector A Offset Learning At Min Limit
- P02D9Cylinder 7 Fuel Injector A Offset Learning At Max Limit
- P0281Cylinder 7 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.