C0661 code meaning
Left Rear Wheel Speed Sensor B Circuit Low
What C0661 means
With C0661 the second left rear speed signal sits below the lowest level an intact sensor ever outputs, typically because the signal lead touches ground or the sensor feed has collapsed. No carmaker documents this code. What normal looks like is shown by a Motor magazine measurement on Honda sensors: a healthy unit switches cleanly between about 0.70 V and 1.40 V with a 50 % duty cycle, and a pickup magnet held against the sensor tip makes it switch. A level that stays below the lower band therefore points to wiring rather than to the encoder. Rear wheel speeds matter beyond ABS: in an HL Mando design the electric parking brake on the rear wheels uses them to calculate slip and backs off before a wheel locks during an emergency stop.
C0661 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0661
- Warning for brake or stability system shortly after start
- Emergency braking support of the electric parking brake may be restricted
Common causes of C0661
- Most likelySignal lead chafed through and touching ground
- PossibleSensor supply pulled down, e.g. by water in the plug
- Less likelySensor B shorted internally
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Lr wss bSensor wiring
What each part of C0661 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 61 | The exact fault in that area. |
What to do next
- Note C0661 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 C0661
What does C0661 mean?
C0661 means "Left Rear Wheel Speed Sensor B Circuit Low". With C0661 the second left rear speed signal sits below the lowest level an intact sensor ever outputs, typically because the signal lead touches ground or the sensor feed has collapsed. It is a generic code, so it means the same on every make.
Is it safe to drive with C0661?
Drive gently and only to a workshop. With C0661 the car can go into limp mode (reduced power) to protect itself.
Will C0661 fail an emissions test?
C0661 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 C0661 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will C0661 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.