Code Definition

P1605 — Knock Control CPU malfunction/Engine Stall History

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Toyota

About P1605

P1605 is a manufacturer-specific powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1605 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This fault code sets when the Engine Control Module (ECM) detects an abnormal internal condition in its knock control processor, or when it records a history of unexpected engine stalling, depending on the application. The ECM uses knock sensor inputs and an internal CPU to retard ignition timing when detonation is detected, protecting the engine. If that internal processor does not operate correctly, or the ECM logs an engine stall that was not commanded by the driver, this code is stored. Symptoms range from none with only a stall history recorded, to a check engine light, possible timing re...

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