B1603
Low Severity (Level 2)Lamp Anti-Theft Indicator Circuit Failure
B1603 usually means lamp Anti-Theft Indicator Circuit Failure.
Can you still drive with B1603?
⚠️Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
Typical repair cost: $100 – $800
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
- Security light flashing — vehicle may not start
- Warning light or message on dashboard related to the vehicle security/anti-theft system
- Security system not functioning as expected
- Diagnostic trouble code (DTC) stored in module memory
Possible Causes
- Failed security module — internal fault from age, heat cycling, and vibration
- Damaged wiring or corroded connector in the vehicle security/anti-theft system circuit
- Blown fuse for the vehicle security/anti-theft system circuit — check before replacing components
- Faulty control module driving the security module
- Loose or corroded ground point shared by the vehicle security/anti-theft system
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 ($35-87 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, $87 diagnostic fee at shop)
- If the engine cranks but won't start, check the security/immobilizer light — if flashing, try a different key. Key programming may be needed ($105-454 at dealer or locksmith)
- Replace security module if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($100-800)
- Check and replace any blown fuses in the vehicle security/anti-theft system fuse circuit — if fuse blows again, there's still a short that needs to be found ($3-17 for fuses)
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 B1603 mean?
B1603 stands for "Lamp Anti-Theft Indicator Circuit Failure". B1603 usually means lamp Anti-Theft Indicator Circuit Failure.
Can you drive with B1603?
Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
How much does it cost to fix B1603?
Repair costs for B1603 typically range from $100 to $800, 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 ($35-87 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, $87 diagnostic fee at shop); If the engine cranks but won't start, check the security/immobilizer light — if flashing, try a different key. Key programming may be needed ($105-454 at dealer or locksmith).
Will B1603 clear itself?
Explore Repair Costs
Related OBD-II Codes
These codes are in the same range as B1603 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 B1603 discussions in the community