P2159 Vehicle Speed Sensor B Range/Performance
OBD-II Trouble Code Technical Description
Vehicle Speed Sensor "B" Range/Performance
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles, including but not limited to Honda, Proton, Kia, Dodge, Hyundai, VW, Jeep, etc.
Although generic, the specific repair steps may vary depending on make/model.
What does that mean?
Basically a P2159 trouble code means that the vehicle's speed as read by the Vehicle Speed Sensor (VSS) "B" is outside of the expected range (too high or low for example). The VSS input is used by the vehicle's main computer called a PCM/ECM powertrain/engine control module along with other inputs for proper operation of the vehicle systems.
How The VSS Works
Typically, the VSS is an electromagnetic sensor that uses a rotating reluctor ring to complete an input circuit to the PCM. The VSS is mounted in the transmission housing at such a position as to allow the reluctor ring to pass by it; in close proximity. The reluctor ring is attached to the output shaft of the transmission so that it spins along with it.
As the reluctor ring passes by the electromagnetic tip of the VSS, notches and grooves serve to complete and interrupt the circuit rapidly. These circuit manipulations are recognized by the PCM as transmission output speed or vehicle speed.
A typical VSS or vehicle speed sensor:
This code is different from the P2158 code in the fact that it may not trigger the malfunction indicator light (MIL). Potential symptoms are basically the same as the P0500 VSS code:
- loss of anti-lock brakes
- the "anti-lock" or "brake" warning lamps on the dash may be lit
- the speedometer or odometer may not work properly (or at all)
- your vehicle's RPM limiter may be decreased
- the shifting of an automatic transmission may become erratic
- other symptoms may also be present
A P2159 DTC trouble code may be caused by one or more of the following:
- The Vehicle Speed Sensor (VSS) "B" is not reading (functioning) properly
- There is a broken/frayed wire leading to the vehicle speed sensor
- The vehicle's PCM is not correctly configured for the actual tire size on the vehicle
Diagnostic & Repair Steps
A good first step to do as a vehicle owner or DIYer is to search for technical service bulletins (TSBs) for your particular vehicle make/model/engine/year. If a known TSB exists (as is the case for some Toyota vehicles), following the instructions in a bulletin can help you save time and money in diagnosing and repairing your issue.
Next, visually inspect all wiring and connectors that lead to the speed sensor. Look closely for any chafing, bare wires, broken wires, melted, or otherwise damaged areas. Repair as required. The location of the sensor depends on your vehicle. The sensor could be on the rear axle, transmission, or perhaps the wheel hub (brake) assembly.
If the wiring and connectors are OK, then check the voltage at the speed sensor. Again, the exact procedure will depend on your make and model of vehicle.
If everything looks OK, replace the sensor.
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