B1678
Low Severity (Level 2)Alarm Panic Input Circuit Open
B1678 usually means alarm Panic Input Circuit Open.
Can you still drive with B1678?
⚠️Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
Typical repair cost: $110 – $900
Severity Level 2 — Low
This code indicates a minor issue that is unlikely to cause immediate driveability problems. You can typically continue driving but should have the vehicle inspected at your earliest convenience.
Common Symptoms
- Engine cranks but won't start — immobilizer preventing start
- Alarm going off randomly or not arming
- Security system working intermittently, then stopping completely
- Infinite resistance in the vehicle security/anti-theft circuit — broken wire or disconnected connector
Possible Causes
- Broken wire or connector pin in the vehicle security/anti-theft system harness — common at flex points like door jambs or where wiring moves
- Disconnected or loose electrical connector — may have been bumped during other repairs
- Failed security module — internal open circuit from age, heat cycling, or vibration
- Corrosion completely severing a wire or connector terminal — green crust on copper wiring
- Wiring harness damage from rodent chewing — look for nesting material near the engine or under dash
Common Fixes
- Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($16-121 at shop, free at auto parts store for basic scan)
- Visually inspect the vehicle security/anti-theft system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $120 diagnostic fee at shop)
- Trace the vehicle security/anti-theft system wiring from connector to connector with a multimeter set to continuity/resistance mode — find and repair the break in the circuit ($122-287 labor for diagnosis and repair)
- Check and reseat all connectors in the vehicle security/anti-theft system circuit — disconnect, inspect pins, clean with electrical contact cleaner, apply dielectric grease, and reconnect firmly ($15 DIY or $62 shop minimum)
- If security module has failed internally (open circuit inside), replace it — don't try to repair sealed components ($100-800)
Estimated Repair Cost
These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.
Frequently Asked Questions
What does B1678 mean?
B1678 stands for "Alarm Panic Input Circuit Open". B1678 usually means alarm Panic Input Circuit Open.
Can you drive with B1678?
Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
How much does it cost to fix B1678?
Repair costs for B1678 typically range from $110 to $900, depending on your vehicle make, model, and local labor rates. Common fixes include: Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($16-121 at shop, free at auto parts store for basic scan); Visually inspect the vehicle security/anti-theft system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $120 diagnostic fee at shop); Trace the vehicle security/anti-theft system wiring from connector to connector with a multimeter set to continuity/resistance mode — find and repair the break in the circuit ($122-287 labor for diagnosis and repair).
Will B1678 clear itself?
Explore Repair Costs
Related OBD-II Codes
These codes are in the same range as B1678 and often share similar causes and fixes.
Worried about repair costs?
Get transparent estimates and verify your mechanic's quote before authorizing repairs.
Related Discussions
See what other car owners are saying about this code and related repairs.
View B1678 discussions in the community