The B1305 OBD2 fault code relates to the Accessory Delay Relay Coil circuit. This monitors oil level or temperature. When the circuit circuit failure, oil monitoring is compromised.

At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix.

Symptoms

• Oil level/temperature warning
• Incorrect oil readings
• Possible engine protection mode

Common Causes

• Failed sensor — internal damage
• a general circuit failure is detected — can result from wiring faults, connector issues, or component failure
• Wiring issues — damaged harness
• Low oil level — actual low oil

Step-by-Step Diagnosis

1. Scan with OBD2 tool — Confirm B1305.
2. Check oil level — Verify actual oil level.
3. Inspect sensor — Check wiring and connector.
4. Test sensor — Compare to specs.

Repair & Solutions

• Replace sensor if faulty.
• Add oil if low.
• Repair wiring.

Related Codes

• B1302 — Accessory Delay Relay Coil Circuit Failure
• B1303 — Accessory Delay Relay Coil Circuit Open
• B1304 — Accessory Delay Relay Coil Circuit Short To Battery

External References

- OBD2Pros — Complete DTC Reference

About This Guide

This diagnostic article is an original guide created by AIscanAuto for educational and troubleshooting purposes. The technical information about OBD2 DTC codes is based on publicly available automotive diagnostic standards and industry best practices. External links provided in the "External References" section are for additional reading and context only — they do not imply endorsement or ownership of third-party content. All repair procedures should be performed by qualified technicians.