P0802
Transmission Control System MIL Request Circuit/Open
The dedicated MIL request line from the TCM to the ECM (used in older systems where modules used a hard wire to ask for the MIL instead of CAN messaging) is open. The ECM cannot honour TCM-side MIL requests.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
Ordered by how often each turns out to be the cause.
- Open MIL request wireCommon
- Pin pushed back out of connector bodyLess likely
- Cracked solder joint inside the module or sensorLess likely
Parts involved
- MIL Request Wire
- TCM
- ECM
P0802 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.