P2B95: Cold-start multi-pulse fueling misses opening events across the engine

P2B95 monitors missing injection pulses across the engine during the reviewed GM cold-start emissions-reduction strategy. It accumulates missed-pulse evidence relative to total pulses when multi-pulse fueling is active, rather than naming one particular cylinder.

The test opportunity is short and conditional

Initial conditions include catalyst temperature below 550°C, coolant above minus 12°C and at or below 66°C, and barometric pressure at least 70 kPa. Multi-pulse operation also requires engine speed from 250 to 3,000 rpm and runtime below 20 seconds in the displayed enable row.

The test runs once per trip while the cold-start strategy and dual-pulse operation are active. It ends when dual pulse stops or the first 500 engine cycles are reached. A long warm-engine drive therefore does not replace the specific startup opportunity.

Opening feedback, not commanded pulse count alone

The ECM looks for the injector voltage signature of opening. Missing detectable opening magnitude, or a metric failing its calibrated threshold on any pulse of any cylinder, supplies the evidence. Small-pulse enable and feedback-data-ready status must be true.

The continuation excludes multiple protective and service operating modes and related sensor or circuit faults. A missing result may reflect an inhibited strategy rather than successful pulse delivery.

Verification should capture an eligible startup window and confirm accepted opening feedback across the monitored pulses. This global code does not prove every injector is faulty or identify the individual cylinder. The source lists Type B, two-trip behavior without a universal parts recommendation.

Source and applicability

This description is limited to the stated monitor; vehicle, engine and calibration matching remain necessary. GM diagnostic table, PDF page 680. GM diagnostic table, PDF page 681. GM diagnostic table, PDF page 682. GM diagnostic table, PDF page 683.