DTC P0300-P0306: Engine Misfire Detected: Description

1999 GMC Forward Control 5.7 R, AutomaticSECTION Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 Pontiac Grand Prix, 2002 Pontiac Bonneville, 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, and 2002 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

Powertrain Control Module (PCM) uses information from Ignition Control (IC) module and Camshaft Position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring variations in crankshaft rotation speed for each cylinder, PCM is able to detect individual misfire events. A misfire rate that is high enough can cause 3-way catalytic converter to overheat under certain conditions. Malfunction Indicator Lamp (MIL) will flash on and off when conditions for 3-way catalytic converter overheating are present.

RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.