Left Reverse Light Circuit Malfunction
What does B0042 mean?
The B0042 code means the vehicle's onboard diagnostic system has detected: Left Reverse Light Circuit Malfunction. This is a moderate severity code.
Common Symptoms
- Left reverse light not working when in reverse
- Backup camera display dim on left side
- Only right reverse light illuminates
- Reverse light warning on dash
- Difficulty seeing behind vehicle at night when backing up
Probable Causes (Ranked by Likelihood)
- Burned out left reverse light bulb Very High
- Corroded reverse light socket High
- Faulty reverse light switch on transmission Moderate
- Wiring damage in rear harness Low
Step-by-Step Diagnostic Procedure
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Inspect left reverse light bulb
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Check bulb socket for corrosion
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Test voltage at socket when transmission is in reverse
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Check reverse light switch on transmission
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Inspect wiring from switch to rear light assembly
Frequently Asked Questions
Can I pass inspection with one reverse light out?
It depends on your state. Some states require both reverse lights to be functional for inspection, while others only require one. Check your local regulations.
Where is the reverse light switch?
On most vehicles, the reverse light switch is located on the transmission housing. On some newer vehicles, the signal comes from the transmission range sensor or the powertrain control module.
Will this affect my backup camera?
Usually no. The backup camera has its own power source and is activated by a separate signal from the reverse gear position. However, some systems may dim the camera image if reverse lights are not working.