ok, i have a 2000 B5 S4, 6 speed. a friend upgraded his ECU and gave me his MTM stage 1 M box ecu. I converted to Hitachi Maf, Coded the ECU to 06611 for no ESP and recoded the Instrument cluster to 1025 for the Mbox ecu. Runs awesome, no issues spikes 17 psi holds 13. The issue im having, is now the epc light comes on but only with key on, turns off when i start the car, and with key on the CEL doesnt light up anymore, i purposly triggered the maf and unplugged a power output stage to trigger a CEL and it doesnt illuminate, also in vagcom i did a cluster output test and the cel does come on. so somewhere from switching abox to mbox i lost the CEL. id like to have it back even tho i dont care to ever see it haha. Where did i go wrong>?

Edit, i will also add there are no communication faults between ecu and cluster its working fine,

The engine isnt throwing any codes, but on key on the cel dont light up like normal, and so i purposly set misfire and maf codes to see if it would come on, and it doesnt, even tho when i check codes there are misfire and maf codes like i made happen. The CEL just isnt working, and the ESP light comes on with key on and it previously didnt, however im not concerned with that as the car doesnt have ESP as its a 2000, but id like the CEL to function as normal. Thanks for the quick reply!

Put your cluster back to 0.

No worries. If the you get a P1650, don't worry about it. You can remove it with CW_CAN_R when you get more comfortable. In the meantime, it won't cause a CEL.