B1491
Moderate Severity (Level 3)Ignition Cylinder Sensor Circuit Failure
B1491 usually means ignition Cylinder Sensor Circuit Failure.
Can you still drive with B1491?
⚠️Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
Typical repair cost: $100 – $600
Severity Level 3 — Moderate
This code indicates a moderate issue that may affect vehicle performance and fuel economy. Continued driving is possible in most cases, but prompt diagnosis and repair are recommended to prevent further damage.
Common Symptoms
- Warning light or message on dashboard related to the ignition system
- Check Engine Light illuminated
- Ignition not functioning as expected
- Diagnostic trouble code (DTC) stored in module memory
Possible Causes
- Failed ignition module/switch — internal fault from age, heat cycling, and vibration
- Damaged wiring or corroded connector in the ignition system circuit
- Blown fuse for the ignition system circuit — check before replacing components
- Faulty control module driving the ignition module/switch
- Loose or corroded ground point shared by the ignition 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 ($22-124 at shop, free at auto parts store for basic scan)
- Visually inspect the ignition system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $96 diagnostic fee at shop)
- Replace ignition module/switch if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($100-600)
- Check and replace any blown fuses in the ignition system fuse circuit — if fuse blows again, there's still a short that needs to be found ($3-12 for fuses)
- Perform a wiggle test on the ignition system wiring harness while monitoring live data — see if the fault returns when you move the harness at different points ($0-136 diagnostic labor)
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 B1491 mean?
B1491 stands for "Ignition Cylinder Sensor Circuit Failure". B1491 usually means ignition Cylinder Sensor Circuit Failure.
Can you drive with B1491?
Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
How much does it cost to fix B1491?
Repair costs for B1491 typically range from $100 to $600, 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 ($22-124 at shop, free at auto parts store for basic scan); Visually inspect the ignition system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $96 diagnostic fee at shop); Replace ignition module/switch if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($100-600).
Will B1491 clear itself?
Explore Repair Costs
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