Code Definition

B1388 — Oil Temperature Sensor Circuit Short To Battery

System: Body  |  Type: Manufacturer-Specific  |  Make: Generic

About B1388

B1388 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1388 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and a sensor-related fault — the reported value from the named sensor is out of spec.

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.

B1388 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 body control module monitors the oil temperature sensor signal voltage against expected limits and sets DTC B1388 when the signal voltage rises above what the 5V reference can produce, indicating the signal wire has shorted to a battery voltage source. The oil temperature sensor uses a negative temperature coefficient thermistor; under normal operation the signal sits between approximately 0.3V when hot and 4.8V when cold, so a sustained reading above the reference voltage is impossible from a healthy sensor circuit. The module relies on this temperature value for the gauge driver output, ...

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