Continuous Memory Self-Test

WARNING: This page is about a different car, the 2002 Mazda B4000, 2002 Mazda B3000, and 2002 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.

Continuous memory DTCs are set when a continuous memory self-test is performed. Continuous memory self-test is a functional test of PCM performed under any condition (engine running or off) with ignition on. Unlike KOEO and KOER self-tests which can only be activated on demand, continuous memory self-test is always active in monitoring the system. When a fault is detected, DTC will be stored in memory. This makes it possible to diagnose intermittent faults.

There are 2 types of continuous memory DTCs. First type is emission-related and will illuminate the Malfunction Indicator Light (MIL) located in instrument cluster. The second is a non-emission related and will never illuminate MIL.

For emission-related MIL codes, Powertrain Control Module (PCM) will store DTC in continuous memory when a fault is detected for the first time. At this point, DTC will not illuminate MIL and is considered a pending code. If same fault is detected after next ignition start-run cycle, emission-related code will illuminate the MIL. The MIL will remain on even if fault is intermittent. The MIL will be turned off if fault is not present through 3 consecutive drive cycles, or if PCM reset is performed. Also, an emission-related pending code and non-emission related codes will be erased after about 40-80 vehicle warm up cycles or PCM reset.