P0898 Transmission Control System MIL Request Circuit Low

P0898 indicates the transmission control system MIL request circuit is low. The transmission controller's request path to illuminate the MIL is pulled low or missing.

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 there is no transmission fault because the lamp request path itself is faulty.

Symptoms of P0898

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 P0898

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 transmission, communication, and MIL-request codes to identify the fault behind the lamp request issue.
Check the MIL request circuit or network message path, TCM power and grounds, connector condition, and module communication status.
Verify whether the engine controller receives the transmission fault request and whether the TCM is online when the code sets.

Related OBD-II codes

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