Code Definition

P1600 — Low battery voltage to Powertrain Control Module

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

About P1600

P1600 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.

When P1600 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

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.

P1600 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 that its battery supply voltage has dropped below the calibrated minimum threshold, either during cranking or normal operation. The ECM needs a stable battery feed to run its processor and hold learned memory, so it monitors the backup and ignition supply voltages. A low or interrupted supply can reset learned values, disturb engine management, and reduce system reliability. The fault is stored when the voltage stays too low for a set time. The driver may notice hard starting, stalling, erratic running, repeated relearns, and a ...

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