OBD
P0899
Transmission Control System MIL Request Circuit High
What it means
P0899 means Transmission Control System MIL Request Circuit High.
Check these first
- An open in the MIL request wire
- A failed TCM
- A backed out MIL request connector pin
- A PCM that misreads the MIL request
What to do next
- Read the MIL request circuit state on a scan tool
- Test the MIL request wire for an open
- Wiggle test the MIL request connector
- Check the TCM for other faults
- Replace the TCM if the circuit stays high
- Clear the code and retest
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Updated
Generic SAE J2012 definition. Last updated 2026-10-10.