Code Definition

B2798 — Immobiliser system communication problem

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Toyota

About B2798

B2798 is a generic (obd-ii standard) body diagnostic trouble code recorded for Toyota vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B2798 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

This DTC is stored by the Toyota Engine Control Module (ECM) when it does not receive the correct key verification response from the immobiliser ECU or certification (smart key) ECU within the specified time window during the ignition ON or engine start sequence. The ECM relies on this encrypted authentication response to confirm a valid key before enabling fuel and ignition. B2798 sets when the response is missing, late, or invalid, which can result from a communication line fault, a module mismatch or pairing problem, or corrupted key registration data. When this code is active the engine wi...

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