B1845 – Ignition Tamper Circuit Failure

The ODBII code B1845 indicates a malfunction in the ignition tamper circuit, which is responsible for detecting unauthorized access or tampering with the ignition system.

The severity of ODBII code B1845 is moderate.

Common Causes For: B1844 Phone Handset Circuit Failure

• Faulty ignition switch
• Damaged wiring or connectors in the ignition circuit
• Malfunctioning anti-theft system
• Defective body control module (BCM)
• Poor ground connections
• Corroded terminals
• Faulty key or key fob
• Issues with the ignition lock cylinder

Common misdiagnosis for B1845 Ignition Tamper Circuit Failure

• Faulty ignition switch
• Defective body control module (BCM)
• Wiring issues or shorts in the ignition circuit
• Malfunctioning key fob or transponder
• Battery or charging system problems
• Faulty anti-theft system components
• Incorrectly programmed key or keyless entry system
• Issues with the vehicle’s computer or software glitches

Common Troubleshooting Steps

The OBD-II code B1845 refers to an “Ignition Tamper Circuit Failure.” This code is typically associated with issues in the vehicle’s security or ignition system. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues.
• Inspect Wiring and Connectors: Examine the wiring and connectors associated with the ignition system and the tamper circuit. Look for signs of damage, corrosion, or loose connections that could cause intermittent failures.
• Test the Ignition Switch: The ignition switch can sometimes be the source of the problem. Test the ignition switch for proper operation and ensure it is making good contact in all positions.
• Check the Security System: If your vehicle is equipped with an anti-theft or security system, ensure that it is functioning correctly. A malfunctioning security system can trigger tamper codes.
• Inspect the Body Control Module (BCM): The BCM often plays a role in monitoring the ignition tamper circuit. Check for any faults or issues with the BCM, and ensure it is receiving proper power and ground.
• Examine Fuses and Relays: Check the fuses and relays associated with the ignition and security systems. A blown fuse or faulty relay can cause circuit failures.
• Perform a Visual Inspection: Look for any signs of tampering or modifications to the ignition system or wiring that could lead to this code being triggered.
• Clear the Code and Test Drive: After performing any repairs or adjustments, clear the code using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult Service Manual: Refer to the vehicle’s service manual for specific diagnostic procedures related to the B1845 code. This can provide additional insights and steps tailored to your vehicle’s make and model.
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with your vehicle’s specific systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the B1845 code.