|Code||Fault Location||Probable Cause|
|P0501|| Vehicle speed sensor (VSS) -range/performance problem |
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|Wiring, speedometer, VSS, CAN data bus|
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What Does Code P0501 Mean?
The vehicle speed sensor (VSS) is used by various control modules to maintain vehicle performance, engine efficiency, transmission operation, cruise control, stability and traction control, supplemental restraint system, and others. Whether used to determine shift points or verify transmission operation, the VSS signal is critical to many vehicle systems.
The VSS itself may be mounted in the transmission or somewhere else in the drivetrain, such as on the rear differential. Some vehicles have no VSS, but rely on a generated signal from the anti-lock brakes, traction control module, or instrument cluster, based on wheel speed sensor (WSS) information. If the ECM detects a problem with the VSS signal, it will illuminate the check engine light (CEL) and set a diagnostic trouble code (DTC) in system memory. It will likely put the entire system into limp-home mode.
What are the common causes of code P0501 ?
Depending on year, make, and model, DTC P0501 may have number of causes. Here are some of the most common.
- Faulty VSS or VSS Circuit – Age and mileage are the most common VSS killers. After testing for circuit problems and being unable to get a signal from the VSS, you can usually safely condemn the VSS.
- Broken Gear – Many VSS are driven by a gear in the transmission or differential. Broken teeth on either gear could lead to an erratic VSS signal. VSS replacement or transmission repair may be required.
- Metal Flakes – Some VSS generate their signal from a reluctor ring, much like crankshaft position sensors. Excessive metal flakes could gather on the magnetic tip of the VSS, distorting the signal. Cleanup is usually sufficient to restore VSS signal clarity, though more investigation may be required to discover the source of the flakes.
What are the symptoms of code P0501 ?
If there is a problem with the VSS, you probably won’t notice any major problems, but certain systems may not function well. The automatic transmission may shift too harsh, too early, or too late. Cruise control will likely be locked out, as will electronic stability control and anti-lock brakes. The speedometer and odometer may not function, and engine power may be limited. Transmission damage is not common, but possible.
How do you troubleshoot code P0501 ?
Range and Performance DTCs are set when the signal is not within the expected range or changes too quickly, such as VSS changing too rapidly (VSS drops instantly to 0 mph and back to 55 mph, while cruising at 55 mph) or being out of sync with a WSS (VSS reports 0 MPH while the WSS reports 55 mph). VSS range and performance DTCs could be related to circuit or sensor faults, as well as faults in the mechanical system to which is it connected.
- Circuit Check – Check first the circuit between the ECM and VSS. There should be 0 Ω resistance between the ECM and VSS, and >10 kΩ to power or ground. With the VSS plugged in and ignition “On,” three-wire VSS should have a good 5 V reference voltage and solid ground.
- Sensor Check – With the wheels off the ground, you can test a three-wire VSS by measuring a DC pulse, with your multimeter, on the signal wire and rotating the wheels slowly. You can measure a two-wire VSS by measuring an increasing AC voltage and driving the wheels at higher speeds.
Codes Related to P0501
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