B0104 code meaning
Sensor Cleaning Air Blower Actuator A Control Relay
What B0104 means
B0104 points at the relay that switches power to blower A. A fan motor draws more current than a module output can carry, so a relay is a natural choice: the module energises the coil (terminals 85/86 in HELLA's scheme) and the contact (30/87) feeds the motor. HELLA's relay brochure explains that coils may carry a diode or resistor against switch-off spikes and that relays are checked for coil resistance and contact voltage drop. Faults here are an open or shorted coil, welded or burnt contacts, or a missing feed. Ford's US12115948B2 places the blower on the sensor bracket, and the Ford tiara uses that air to shield lenses from insects, as eeNews reports. No carmaker publishes B0104; the B-side relay is B0105.
B0104 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.2 to 1 hours
- Clears after repairWhen cleared with a scanner
Symptoms of B0104
- Blower A dead, or running without command if contacts are welded
- No relay click when cleaning is requested
- Sensor cleaning warning with possible loss of assistance functions
Common causes of B0104
- Most likelyBurnt or welded contacts in the blower A relay
- PossibleRelay coil open or its control wire interrupted
- PossibleBlown fuse or loose socket on the relay supply side
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Sensor cleaning air blower relay aRelay control circuitSensor cleaning air blower a
What each part of B0104 means
| B | Body system: airbags, seat belts, power seats, lights and climate control. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 04 | The exact fault in that area. |
What to do next
- Note B0104 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about B0104
What does B0104 mean?
B0104 means "Sensor Cleaning Air Blower Actuator A Control Relay". B0104 points at the relay that switches power to blower A. It is a generic code, so it means the same on every make.
Is it safe to drive with B0104?
Drive gently and only to a workshop. With B0104 the car can go into limp mode (reduced power) to protect itself.
Will B0104 fail an emissions test?
B0104 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is B0104 to fix?
Difficulty: easy. A typical repair takes 0.2 to 1 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will B0104 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.