Mitsubishi BSW Service Required
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Mitsubishi owners may see a dashboard warning stating BSW Service Required. This message appears when the blind spot monitoring function malfunctions. While this error message appears, you must turn your head when changing lanes to check the blind spots.
At a Glance
- Meaning: the Blind Spot Warning radar behind the rear bumper has a fault, so BSW and Lane Change Assist are off.
- Check mirrors and look over your shoulder until it is fixed.
- First steps: clean the rear bumper corners, remove snow or mud, and restart the car.
- Recent bumper repair or a tow hitch can block or misalign the radar.
- Persistent message: read the radar module codes with a scanner.
What does the BSW service required error mean?
BSW is an abbreviation for the Blind Spot Warning System, a safety feature in many newer Mitsubishi vehicles. It uses a radar mounted behind the rear bumper that monitors the blind spots next to the car.
When it detects an approaching vehicle in the blind spot, it notifies the driver with a symbol on the corresponding outside mirror. An additional feature of this system is Lane Change Assist (LCA). It sounds a warning if you signal a lane change while another vehicle is in the blind spot.
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Symptoms
- “BSW service required” message to show on the vehicle display.
- Inoperable BSW and LCA features, drivers will not be warned about approaching vehicles inside the blind spots.
Possible Causes
A damaged radar sensor behind the rear bumper is the most common problem that triggers the Mitsubishi BSW Service Required warning light. Try pulling over and restarting the vehicle. The vehicle must be diagnosed if the BSW Service Required doesn’t reset.
Foreign objects and external conditions: that interfere with radar operation. Some possible issues include a thick layer of mud and dirt to a heavy rain downpour or snow. The system will regain proper operation after these obstructions are no longer present.
Damaged or misaligned radar assembly: due to the previous collision or after other repairs to the vehicle’s rear end, including bumper removal.
Software issues: and glitches can result in BSW system issues in some specific situations. Installing the latest BSW software version will ensure the system has all the necessary upgrades. To diagnose Mitsubishi BSW Service Required, you must use a Mitsubishi All System Scanner to read the fault codes stored in the BSW Control Module.
One good example of a multi-system scanner is the YOUCANIC Full Systems Scanner. This scanner can read and clear fault codes from all the systems in your Mitsubishi. It can also perform bi-directional tests, maintenance and repair resets, etc.
Clean the rear bumper before you suspect the sensors
The radar units sit behind the plastic of the rear bumper on each corner, and they see straight through paint but not through a layer of packed snow, road salt, mud or ice. A BSW service required message that appears in winter or after a muddy drive very often clears on its own once the bumper corners are washed and the vehicle is restarted. Wash those areas first, before spending anything, because this is the single most common trigger.
Stickers, tow bars and bumper repairs matter
Anything metallic placed over the sensor area will blind it. Bumper stickers with foil backing, a license plate frame relocated to the corner, an aftermarket tow bar bracket or a body shop repair that used metallic filler or a thick layer of primer over the radar zone can all set the warning off permanently. If the message started right after body panels or an accessory was fitted, that is where to look.
Radar aiming is not optional after a bumper comes off
If the rear bumper has been removed, repaired or replaced, the blind spot radars have to be aimed again with diagnostic equipment. Refitting them by eye leaves them pointing slightly wrong, and the module detects the mismatch and shuts the system down with this exact message. A shop that replaced the bumper without recalibrating is a likely cause worth raising with them.
Read the code before replacing a radar unit
Blind spot radars are expensive and the warning message does not say which one failed or why. A scan of the BSW module gives you the specific fault, which commonly turns out to be blockage detected, misalignment or a communication fault on the bus rather than a dead sensor. Checking first is the difference between a wash and a several hundred dollar part.
Frequently Asked Questions
Can I drive with the Mitsubishi BSW warning?
Yes. The car drives normally, but blind spot warning is off, so check your mirrors and look over your shoulder before changing lanes.
Why does BSW turn off in bad weather?
Snow, ice, mud or heavy rain on the rear bumper can block the radar sensors. The system usually comes back once the bumper is clean.
Do BSW sensors need aiming after bumper repair?
Yes. If the rear bumper or a sensor bracket was removed or damaged, the radar sensors may need to be aimed, or BSW may not work correctly.
turns out if the light in the wing mirror is damaged which indicates that there is a vehicle in your blind spot this warning is also displayed