Hi all,

I recently had a problem where I had a P1646/P1647 error code but the CEL was not lit and I believe it should have been. Replacing the upstream O2 sensors cleared the fault codes and the engine now goes into closed loop mode nicely but there remains the puzzle of the CEL. Further, my code reader indicated that the CEL was on even though it wasn't lit!

Just recently I found out that the CEL is supposed to stay on until the engine starts. Mine does not, it lights up during the bulb test but goes out when the bulb test completes. Recently I borrowed an XJ8 and the CEL did indeed stay on until the engine started.

Has anyone experienced this before or can shed any light on what is happening here? Is it just a slightly earlier version of the design of the software? I am concerned I could get another problem and not know about it. Any and all information appreciated.

BTW the red primary fault indicator bulb-tests OK but wasn't lit either.

'99 Sovereign V8 4.0L

Jim

 

Anyone any ideas???

Jim