Failure Conditions

ECM will set a DTC P0300 and illuminate the MIL if 2 misfires per 100 engine revolutions are detected during 2 drive cycles. The misfire rate is measured every 200 revolutions when the following conditions are met:

• Speed change is less than 1000 RPM in a one second period.
• Engine speed is 600-4000 RPM.
• Engine load time is greater than 2.0 mS.
• No fuel cut-off exists.
• Starter is not engaged.
• Vehicle is on a smooth road (acceleration sensor reports less than 0.3 g acceleration).

When misfire rate increases to 5-25 percent per 200 revolutions, there is a danger of catalytic converter damage and MIL will blink on and off. Catalytic converter temperature could exceed 3542°F (1950°C) if misfire rate increases sufficiently. This DTC indicates a problem with cylinder ignition being read by ECM.