What does the P500 fault code mean?
This blog will explain the meaning of the P500 fault code and answer the following questions: what are the causes of the P500 fault code? Where is the wheel speed sensor located in the vehicle? Can you drive the car with a P500 fault code in the ECU?
What does the P500 fault code mean?
The P500 fault code means the signal from any one of the wheel speed sensors is outside of permissible range. The signal is monitored by the electronic stability program control unit and depending on the type of wheel speed sensor, the signal should be within the 0.0 to 250.0 km/hr speed range.
There are four-wheel speed sensors to measure the wheel speed of four wheels. The signal from the wheel speed sensor is responsible for the antilock braking system work. If the vehicle has a traction control system then the same signal is also used to detect excessive wheel slip.
Many car manufacturers also implement the wheel speed signal into a tire pressure loss warning system. The wheel speed of the tire with less or no pressure deviates from the other wheels. Therefore, there is no need for additional sensors in tires to measure the tire pressure and temperature.
The wheel speed sensor can be a hall effect or a magnetic pick-up type. If the wheel speed sensor is a magnetic pick-up type then a multipole ring is integrated into the wheel bearing. The Multipole ring is made up of tiny magnets, the north and south poles are lined up one after another.
Both types of sensors are used today and depending on the control unit programming, they can either be used to detect wheel speed in the forward or reverse direction. The sensors are connected directly to the control unit via electrical lines.
What are the causes of the p500 fault code?
The causes of the P500 fault code are given below
- Faulty wheel speed sensor
The ESP control unit stores fault code P500 when the signal from the wheel speed sensor is implausible. The wheel speed sensor is subjected to hard elements like dirt, rust, and moisture. This causes the sensor to malfunction and detects an incorrect wheel speed signal.
Replacing the faulty wheel speed sensor is the only remedy as it is not possible to clean and reuse it. Many car manufacturers recommend replacing the wheel speed sensors in pairs, for example, if the front left wheel speed sensor malfunctions then both front left and right are replaced together.
The sensors are replaced in pairs in order to avoid repeat repairs and the control unit uses the signals from the other sensors as a plausibility check. Hence, replacing the sensor in pairs ensures reliability.
- Dirty or damaged multipole ring or sensor rotor
The sensor rotor ring consists of teeth or gaps that are detected by the wheel speed sensor. When the teeth are damaged, the sensor fails to register an accurate wheel speed signal. If the wheel speed sensor is a multipole ring type the damaged ring will have the same effect.
A multipole ring is located on the wheel bearing, if there is damage or metal shavings present on the ring; it creates interference between the magnet and the magnetic pickup. Hence, before replacing a wheel speed sensor, the sensor rotor or multi-pole ring is inspected for damage or metal shavings.
- open/ short circuit in the electrical lines
All four-wheel speed sensors have two electrical lines each. The control unit provides a power supply directly to the sensors. If the electrical lines get a short circuit with each other or an open circuit, then the wheel speed signal will not reach the ESP control unit.
A socket box is used to check for short circuits in the wheel speed sensor electrical circuits because the control unit stops sending supply to the wheel speed sensor if there is an electrical short circuit or open circuit.
A short test drive or actual values are checked after performing repairs to the electrical wiring harness. If the wheel speed signal is within the range then the vehicle can be safely driving without the risk of locking up the wheel.
- Internal control unit malfunction
The ESP control unit monitors the wheel speed signal from all four sensors. The power supply required for the sensors is also supplied by the control unit. Therefore, if the fault P500 is still present after replacing the wheel speed sensor and the sensor rotor is okay.
The cause is likely to be the ESP, there is no repair measure for internal malfunction of the ESP control unit. It is replaced and the new control unit is programmed in before the vehicle is safe to drive. It is unlikely that all four-wheel speed sensors fail at the same time so it is possible to interchange the sensor and test it before replacing the control unit.
Where is the wheel speed sensor located in the vehicle?
The wheel speed sensor is located in the steering knuckle or near the wheel hub of the vehicle. The sensor rotor or the multipole ring is also mounted to the wheel hub or bearing, wheel speed sensor must be within 2-3mm of the sensor rotor in order to detect the wheel speed and send the appropriate signal.
All the wheel speed sensors come with a wiring harness, the electrical connector is present behind the fender lining. There are plastic locks that hold the electrical line away from the suspension and the rotating wheel.
To replace a wheel speed sensor, the wheel must be removed, and depending on the location of the complete or partial fender lining is also removed to gain access to the electrical coupler. Ensure that the coupler is properly installed because after putting everything back together it is not possible to check it.
Can you drive the car with a P0500 fault code in the ECU?
No, it is not possible to drive the car with a P0500 fault code stored in the DTC memory of the control unit. The traction control system receives implausible wheel speed signals from the malfunctioning sensor.
This implausible signal is detected as a wheel slip and the traction control unit tries to apply brakes to the wheel with the malfunctioning sensor. After several attempts the ESP control unit becomes inoperative.
The ESP control unit sends the wheel speed data to multiple control units on a CAN data bus and the electronic power steering control unit is also one of the control units that receives the wheel speed signal for operation. Hence the steering wheel also becomes hard to operate.
Other articles about Vehicle Fault Codes you may be interested in
The fault code P0500 is a critical one and it must be rectified as soon as possible. The vehicle may need to be towed to the workshop when the fault occurs. The repair cost depends on the car manufacturer and the repair instructions.