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P0501 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.

Definition

P0501; Vehicle Speed Sensor Range/Performance error, A diagnostic trouble code problem code P0501 implies the Vehicle Speed Sensor (VSS) reading speed of the vehicle is outside the anticipated range (too high or low).

Meaning

The VSS input is utilized with other information for the appropriate functioning of car systems by the vehicle's primary computers, known as the PCM/ECM powertrain control module /engine control module.

Various control modules employ the Vehicle Speed Sensor (VSS) to maintain car performance, motor efficiencies, drive operation, cruise control, stability and traction control, and the complementary restraint system. The VSS signal is essential for many automotive systems to determine shift points or check transmission performance.

The VSS can be placed on the transmission or elsewhere, such as the rear axle. Some vehicles do not have a VSS; instead rely on a signal that comes from the Anti-Lock Brakes, traction control module or instrument cluster using information from a Wheel Speed Sensor (WSS). When the ECM detects a VSS signal issue, it lights up the Check Engine Light (CEL) and sets a DTC into your system memory. It will probably put the whole machine in limp-home mode.

Causes of DTC P0501 Code

The possible causes leading to the development of on-board diagnostic II (OBDII) diagnostic problem code P0501 are:

  • Cables or connections to the VSS sensor may be faulty.
  • Defective speed sensor vehicle.
  • The VSS voltage requirements are not in place since they bounce up or down more quickly than the PCM anticipates.
  • The voltage output of the VSS is lower than predicted, and the output speed of the genuine speed limit is lower than average.
  • Many VSS are powered by a transmission or differential gear. Broken teeth might lead to an inconsistent VSS signal on any gear. Replacement or repair of transmission VSS may be necessary.
  • The PCM setup may not be correct for the size of the tyres of the vehicle.

Symptoms DTC P0501 Code

Following are the possible symptoms of the P0501 code error. There may also be other signs, but these are common and associated with P0501. 


  • Decrease of the RPM (revolution per minute) limiter.
  • The check engine light has been activated, and the code has been placed in the ECM memory.
  • The anti-lock brakes may be lost.
  • The automated transmission shift might be unreliable.
  • The speedometer or odometer may not function correctly (or at all).
  • Due to the irregular transmission change, the engine may appear to be low in power.

Diagnosis

This problem code can be easily diagnosed. One can quickly diagnose this code error in the mechanic shop or DIY.

  • Technicians initially use their scanners to scan PCM codes and document information.
  • Then, all cables and connectors leading to the speed sensor are visually inspected. See carefully for any exposed wires, broken wires, melted regions or otherwise damaged areas. Repair as necessary. The sensor placement depends on the car. The sensor might be mounted on the rear axle, the transmission or maybe the wheel hub. When the cable and connections are OK, check the speed sensor voltage. Again, the precise method depends on car fabric and model.
  • DTCs are set if the signal is not within the anticipated range or changes too fast; for example, VSS changes too fast (VSS falls immediately to 0 mph and returns to 55 mph when cruising) or is out of sync with a WSS (VSS reports 0 MPH while the WSS reports 55 mph). DTC performance and range of VSS might be associated with circuit or sensor failures and mechanical system faults to which it is attached.
  • Circuit Check — First, check the ECM-VSS circuit. The resistance between ECM and VSS should be 0Ω, and >10 k Ω for power or ground. The 3-wire VSS should have a 5 V reference voltage and solid ground when connected with the VSS and ignition "On."
  • Sensor control – With the wheels off the ground, a three-wire VSS may be tested by detecting the DC pulse on the signal wire and gently turning the wheels using a multimeter. By detecting increased AC voltage and moving wheels at faster speeds, one can measure a two-wire VSS.

Common mistakes when diagnosing the P0501 code

The common mistake that can be encountered while addressing the P0501 code error could be: 

  • Missing to check whether  the old sensor output is faulty before the VSS is replaced.
  • Do not remove and inspect excessive metal particles from the VSS, which indicates a problem with internal or back axle components.

How serious is P0501?

An error that is easy to diagnose and fix but can cause serious trouble if not fixed properly.

  • Code P0501 shows that the VSS does not operate properly and can cause damage to the transmission and irregular shifting.
  • The Check Engine Light causes an emission test to fail.
  • The rear end type VSS disables the ABS light and disables the ABS.

What repairs can fix the code P0501?

The possible fixtures for the DTC p0501 code error are:

  • Repair or replace any non-corroded connections.
  • Check the voltage of the VSS sensor and check the requirements of the manufacturer. If not, replace it.
  • Replace the back end or transmission of the VSS.
  • Clean up metal particles, remove codes and do a road test for the car.

Codes Related to DTC P0501

These are the codes that are associated with the DTC P0501 code error. 

  • P0500 Vehicle Speed Sensor
  • P0502 Vehicle Speed Sensor Circuit Low Input
  • P0503 Vehicle Speed Sensor Intermittent/Erratic/High
  • P0574 Cruise Control System – Vehicle Speed Too High
  • P0608 Control Module VSS Output "A"
  • P0609 Control Module VSS Output "B"
  • P2158 Vehicle Speed Sensor "B" Circuit
  • P2159 Vehicle Speed Sensor "B" Circuit Range/Performance
  • P215A Vehicle Speed – Wheel Speed Correlation
  • P215B Vehicle Speed – Output Shaft Speed Correlation
  • P2160 Vehicle Speed Sensor "B" Circuit Low
  • P2161 Vehicle Speed Sensor "B" Circuit Intermittent/Erratic/High
  • P2162 Vehicle Speed Sensor "A"/ "B" Correlation
  • C1123 Vehicle Speed Sensor Input Short to Battery
  • C1751 Vehicle Speed Sensor # 1 Output Circuit Short to Battery Voltage
  • C1752 Vehicle Speed Sensor # 1 Output Circuit Short to Ground

Conclusion

The DTC P0501 is an OBD-II code error related to the vehicle speed sensor's (VSS) performance and range. One can quickly solve this error at home using technical service bulletins (TSBs) and DTC scanners. However, a little previous knowledge is required for DIY. As mentioned, this code can cause serious trouble to the engine power or transmission system, so one should take this error very seriously. Hence the best practice is to check the vehicle by an expert for a smooth ride. 

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