The B1838 OBD2 fault code relates to the Battery Saver Power Relay circuit. When the circuit circuit failure, the module cannot properly monitor or control this body system.
At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix.
Symptoms
- Battery warning light
- Electrical systems losing power
- Possible no-start condition
- Battery drain issues
Common Causes
- Faulty component — internal damage or wear affecting Battery Saver Power Relay
- Wiring issues — broken, corroded, or chafed wires in the circuit
- Connector problems — loose, oxidized, or moisture-damaged pins
- a general circuit failure is detected — can result from wiring faults, connector issues, or component failure
- Module input failure — rare, but the control module input stage may be defective
Step-by-Step Diagnosis
- Scan with OBD2 tool — Confirm B1838 is active. Check for additional DTCs.
- Visual inspection — Examine the Battery Saver Power Relay wiring and connector for corrosion or damage.
- Check voltage and ground — Use a multimeter to verify proper reference voltage.
- Test component — Compare readings to factory specs. A stuck or erratic signal confirms failure.
- Check for shorts/opens — Perform continuity tests on the wiring between the component and control module.
Repair & Solutions
- If the component is defective, replace the Battery Saver Power Relay with an OEM or quality aftermarket part.
- Repair any damaged wiring or connectors using proper methods.
- Clear the DTC with an OBD2 scanner and test drive to verify the code does not return.
- If the code persists after component replacement, inspect the control module connector.
Related Codes
- B1835 — Door Unlock Disarm Output Circuit Open
- B1836 — Door Unlock Disarm Output Circuit Short To Battery
- B1837 — Door Unlock Disarm Output Circuit Short To Ground