Code Definition

B1391 — Oil Level Switch Circuit Failure

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

About B1391

B1391 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 B1391 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

B1391 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 (BCM) or Engine Control Module (ECM) monitors the oil level switch to alert the driver when engine oil is below the safe operating threshold. The oil level switch is a simple float type or thermistor sensor mounted in the oil pan that signals the module via a low current circuit. DTC B1391 is set when the module detects an open circuit, short to ground, short to power, or out of range signal from the switch over multiple ignition cycles. Symptoms typically include an illuminated oil level warning lamp, a service message in the driver information cluster, or a stuck low ...

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