OBD-II Fault Code

B1273: Servo Motor Potentiometer Vent Circuit Open

Meaning, symptoms, likely causes, diagnostic checks and repair guidance for B1273.

System family

Body

Manufacturer-specific

Repair category

EVAP / fuel vapour

Use this category to narrow your checks before replacing parts.

Severity

Low

Severity is a general guide. Confirm with scan-tool data and vehicle symptoms.

What B1273 usually means

Servo Motor Potentiometer Vent Circuit Open.

Common symptoms

Body/accessory warning lamp or feature not working; Fuel smell possible; Usually little drivability change

Likely causes

Loose/damaged fuel cap; Cracked EVAP hose; Faulty purge/vent valve; Leaking canister; Open circuit; Disconnected connector; Broken wire; Failed component

Diagnostic checks

Check related fuses, connectors, grounds and switch/module power supply; Check fuel cap seal first; Smoke-test EVAP system; Command purge/vent valves with scan tool if available; Check connector fitment and continuity from module to component

Repair guidance

Replace damaged cap/hoses, repair leaks, replace stuck purge or vent valve after testing; Repair open wire/connector or replace the failed component after continuity test

Verification after repair

Operate the affected body/accessory system and rescan

Note: Confirm vehicle make/model/year because manufacturer-specific codes can vary; Manufacturer-specific: confirm definition and test steps in the vehicle service manual. A DTC identifies a circuit or system condition, not always the failed part.