B1004High urgency
Ignition Run Circuit Open
Body · Control Module
⛔ Vehicle may not start or may lose power to critical systems. Service immediately.
What this means
The BCM has detected an open circuit in the ignition run feed — the power supply that activates most vehicle systems when the key is in the Run position.
Likely causes
- Blown ignition run fuseMost common
- Failed ignition switchMost common
- Open in ignition run wiringCommon
Estimated repair cost
Ignition fuse$5 – $25
Ignition switch$80 – $300
Wiring repair$80 – $250
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Frequently asked questions about B1004
What does B1004 mean?
The BCM has detected an open circuit in the ignition run feed — the power supply that activates most vehicle systems when the key is in the Run position.
Is B1004 serious?
Vehicle may not start or may lose power to critical systems. Service immediately.
How much does it cost to fix B1004?
Repair costs for B1004 range from $5 – $25 depending on the root cause and your vehicle.
Can I drive with B1004?
No — this code indicates a serious issue. Stop driving and have the vehicle inspected immediately.