B1791
Low Severity (Level 2)Autolamp Sensor Input Circuit Open
B1791 usually means autolamp Sensor Input Circuit Open.
Can you still drive with B1791?
⚠️Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
Typical repair cost: $60 – $700
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
- Body electronics not working — no response when activated
- Body electronics working intermittently, then stopping completely
- Infinite resistance in the body electrical circuit — broken wire or disconnected connector
- Fault may be intermittent — code may clear itself and reappear
- Reduced vehicle functionality related to the body electrical system
Possible Causes
- Broken wire or connector pin in the body electrical 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 body control module (BCM) or sensor — 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 ($17-112 at shop, free at auto parts store for basic scan)
- Visually inspect the body electrical system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $58 diagnostic fee at shop)
- Trace the body electrical system wiring from connector to connector with a multimeter set to continuity/resistance mode — find and repair the break in the circuit ($144-487 labor for diagnosis and repair)
- Check and reseat all connectors in the body electrical system circuit — disconnect, inspect pins, clean with electrical contact cleaner, apply dielectric grease, and reconnect firmly ($14 DIY or $79 shop minimum)
- If body control module (BCM) or sensor has failed internally (open circuit inside), replace it — don't try to repair sealed components ($50-600)
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 B1791 mean?
B1791 stands for "Autolamp Sensor Input Circuit Open". B1791 usually means autolamp Sensor Input Circuit Open.
Can you drive with B1791?
Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
How much does it cost to fix B1791?
Repair costs for B1791 typically range from $60 to $700, 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 ($17-112 at shop, free at auto parts store for basic scan); Visually inspect the body electrical system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $58 diagnostic fee at shop); Trace the body electrical system wiring from connector to connector with a multimeter set to continuity/resistance mode — find and repair the break in the circuit ($144-487 labor for diagnosis and repair).
Will B1791 clear itself?
Explore Repair Costs
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