P2B02 concerns cylinder 3: in warm operation the ECM did not see the voltage bump that marks the cylinder 3 injector actually opening, often enough to count pulses as not delivered. On GM's 1.2 L LIH three-cylinder, cylinder 3 is the last one, and the 2025 table for that family (cylinders 1–3 only) decides after 50 to 100 samples, Type B. GM service update A202310450 for this engine in the Encore GX (2020–2021) and Trailblazer (2021) (about 22,350 US vehicles) lists P2B02 with P2B00, P2B01 and the cold-start codes; the cure is reprogramming the ECM, not new parts. On four-cylinder engines GM also monitors cylinder 3 with this code. Cold-start faults on the same cylinder are P2B0A.
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 3 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Check engine light, often without any driveability complaint
- On a real injector fault rough running on cylinder 3 (P0303)
Most likely causes
- ECM calibration with false detections (GM 1.2 L LIH, service update A202310450)
- Cylinder 3 injector not lifting reliably
- Damaged injector 3 wiring or connector
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 P2B02 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 02: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B02?
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 P2B02?
The most common causes are: eCM calibration with false detections (GM 1.2 L LIH, service update A202310450); cylinder 3 injector not lifting reliably; damaged injector 3 wiring or connector.
Related codes
- P2B0ACold Start Cylinder 3 Injection Pulse Performance
- P2B01Cylinder 2 Injection Pulse Performance
- P2B03Cylinder 4 Injection Pulse Performance
- P2B96Injection Pulse Performance
- P02F0Cylinder 3 Injector Circuit Range/Performance
- P0203Cylinder 3 Injector A Circuit/Open
- P0303Cylinder 3 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.