P2B00 says the engine module could not confirm, with the engine past its cold-start phase, that injection pulses it commanded for cylinder 1 really happened. GM documents the check for its petrol direct-injection engines: the ECM digitises the voltage across both injector wires and looks for the small flux signature the armature leaves when it lifts. If that opening trace is missing too often – 100 failures in 200 samples in the 2018 four-cylinder table, Type B, lamp after two trips – the pulse counts as lost. GM only runs it with at least 5 MPa rail pressure, 5 s engine run time and 10 % fuel in the tank. GM bulletins name P2B00 on the 2.7 L L3B (chafed engine harness) and the 1.2 L LIH (ECM software). The cold-start twin for cylinder 1 is P2B08.
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 1 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Check engine light after the second faulty trip
- Rough running or misfire on cylinder 1 (P0301), sometimes no noticeable symptom
- With a harness short, several unrelated codes at once and possibly a no-start
Most likely causes
- Engine harness chafed through to ground (GM L3B – above the camshaft carrier or near the left shock tower)
- Armature or needle of the cylinder 1 injector sticking, so no opening signature appears
- Outdated ECM calibration (GM service update for the 1.2 L LIH)
- High contact resistance at the cylinder 1 injector 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 P2B00 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 00: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B00?
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 P2B00?
The most common causes are: engine harness chafed through to ground (GM L3B – above the camshaft carrier or near the left shock tower); armature or needle of the cylinder 1 injector sticking, so no opening signature appears; outdated ECM calibration (GM service update for the 1.2 L LIH).
Related codes
- P2B08Cold Start Cylinder 1 Injection Pulse Performance
- P2B01Cylinder 2 Injection Pulse Performance
- P2B96Injection Pulse Performance
- P02EECylinder 1 Injector Circuit Range/Performance
- P0201Cylinder 1 Injector A Circuit/Open
- P0301Cylinder 1 Misfire Detected
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
- gsi.ext.gm.com: 18OBDG01 Hybrid Diagnostics
- static.nhtsa.gov: MC 10160694 9999
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.