P0303

P0303

DESCRIPTION

NOTE: Refer to DTC P0300.

FAILURE CONDITIONS
The ECM will set P0301, P0302, P0303 or P0304 and MIL will turn on if 2 misfires per 100 revolutions are detected during two driving cycles. The misfire rate is measured every 200 revolutions when the following conditions are met:
- Speed change is less than 1000 rpm per second.
- Engine speed is between 600 and 4000 RPM.
- Engine load is greater than 2 milliseconds.
- No fuel cut-off.
- Starter is not engaged.
- Vehicle on smooth road (acceleration sensor reports less than 0.3 g acceleration).

If the misfire rate increases to between 5% - 25% per 200 revolutions, there is danger of catalyst damage and the MIL will flash and on. The catalyst temperature could exceed 3542 °F (1950 °C) if the misfire rate increases enough. This code indicates a problem with cylinder ignition being read by the ECM.

Circuit Diagram:

Test Procedure: