P0802 Transmission Control System MIL Request Circuit/Open

P0802 points to a transmission control system MIL request circuit or open-circuit fault. The transmission controller cannot properly request the malfunction indicator lamp.

Code details

Generic OBD-II · P0

System: Transmission
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume the absence of a lamp means no transmission fault; the MIL request path itself may be faulty.

Symptoms of P0802

Harsh, delayed, or slipping shifts, or being stuck in one gear.
Check-engine light, sometimes with limp-home mode.
Flaring RPM or a shudder under load.

Common causes of P0802

Low or degraded transmission fluid.
A failing speed sensor, shift solenoid, or pressure-control circuit.
Wiring, connector, or internal hydraulic/mechanical faults.

Useful checks before replacing parts

Scan all modules for communication, MIL request, transmission, and powertrain codes that accompany the fault.
Check module communication wiring, power, grounds, connector condition, and network data used for MIL requests.
Review whether the transmission controller is online and whether the engine controller receives its fault request.

Related OBD-II codes

These nearby transmission entries can help compare wording and pin down the fault area.