Code Definition

P1604 — Startability Malfunction

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

About P1604

P1604 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.

P1604 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

The engine control module monitors how long the engine takes to reach a self sustaining running speed each time it is cranked, using crankshaft position sensor pulses to measure cranking speed and the point at which combustion takes over. DTC P1604 is logged when that period exceeds the expected time, when the engine fails to start altogether after a valid cranking attempt, or when repeated attempts are needed before the engine will run. The module is judging the outcome of the start rather than any individual component, so this is a symptom code that reports a hard starting condition without ...

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