Sporadic Check Engine Light
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New User
Joined: Sep 2003
Posts: 13
Likes: 0
Sporadic Check Engine Light
Hey All. Im wondering if anybody ever encountered a Check Engine Light
that stays on for a day or 2 then goes out for a week or more,then back on for another couple days? I haven't had time to run the code yet but I thought
that the CEL was supposed to stay on once it came on. Could it be the computer about to quit? The truck is a 99 3.0 V6 with 123k on it now.
Performance seems the same whether the light is on or off. Any advice is
appreciated.
that stays on for a day or 2 then goes out for a week or more,then back on for another couple days? I haven't had time to run the code yet but I thought
that the CEL was supposed to stay on once it came on. Could it be the computer about to quit? The truck is a 99 3.0 V6 with 123k on it now.
Performance seems the same whether the light is on or off. Any advice is
appreciated.
Post Fiend
Joined: Dec 2001
Posts: 10,562
Likes: 4
From: South Jersey
The OBD II system monitors for malfunctions either continuously, regardless of driving mode, or non-continuously, once per drive cycle during specific drive modes. A DTC is stored in the PCM Keep Alive Memory (KAM) when a malfunction is initially detected. In most cases the MIL is illuminated after two consecutive drive cycles with the malfunction present. Once the MIL is illuminated, three consecutive drive cycles without a malfunction detected are required to extinguish the MIL. The DTC is erased after 40 engine warm-up cycles once the MIL is extinguished.
