top of page

PEX Aftermarket Position Sensors

Purpose and Function:

​

Position sensors detect the precise position or movement of engine and vehicle components. They provide critical feedback to the ECU or control modules for proper timing, control, and safety. Common heavy-duty applications include:

  • Camshaft & Crankshaft Sensors: Monitor engine timing for fuel injection, ignition, and valve control.

  • Throttle Position Sensor (TPS): Measures throttle plate angle to manage fuel delivery and load.

  • EGR Valve Position Sensor: Monitors EGR valve opening for precise exhaust gas recirculation.

  • Vehicle or Wheel Speed Sensors: Monitor wheel rotation for ABS, traction control, and cruise control systems.

  • Other actuators or lever positions: For transmissions, turbo actuators, or dump valves.

These sensors allow the ECU to optimize performance, emissions, fuel economy, and safety systems

1 

Features & benefits

  • Precise positional feedback for critical engine timing and actuator control.

  • Supports emission compliance through accurate EGR and throttle control.

  • Enhances safety and stability by enabling ABS, traction, and speed-dependent controls.

  • Durable construction designed for vibration, heat, and harsh environments.

  • Many sensors provide digital or analog signals for easy ECU interpretation.

2

Technical Highlights

  • Signal types:

    • Hall-effect: Provides digital pulse or square-wave output, often used in cam/crank sensors.

    • Variable reluctance / inductive: Produces AC sine wave proportional to speed/position.

    • Potentiometric (resistive): Analog voltage varies with throttle or actuator position.

    • Magnetoresistive / GMR: High-accuracy digital output for heavy-duty or precision applications.

  • Sensor placement:

    • Cam/crank sensors near timing gears or flywheel.

    • TPS on throttle body.

    • EGR sensors mounted on the valve actuator or shaft.

    • Speed sensors on wheels or transmission output shafts.

  • Output characteristics: Often frequency, voltage, or resistance, depending on sensor type. Correct signal shape is critical for ECU interpretation.

3

Diagnostic and Testing Tips

  • Visual inspection: Check sensor body, mounting, wiring, and connectors for heat, vibration, or contamination damage.

  • Static tests:

  • Hall/VR sensors: measure resistance or AC output at slow rotation.

  • Potentiometric sensors: check voltage sweep across full movement range.

  • Dynamic tests: Rotate the cam, crank, or actuator shaft while monitoring the waveform on a scope or live data from scan tool.

  • Functional checks:

  • Compare ECU readings to actual shaft/throttle movement.

  • Verify smooth changes with no dropouts or spikes.

  • Replace sensors with erratic signals, open/short circuits, or inconsistent readings. Ensure timing marks and actuator calibration after replacement.

4

Installation Tips and Common Issues

  • Mount sensors securely, aligned to OEM specifications; even slight misalignment can cause signal loss.

  • Maintain proper air gap or rotational clearance for VR/Hall-effect sensors.

  • Route wiring away from heat sources, moving parts, and high-voltage cables.

  • Avoid oil, coolant, or dirt contamination that can alter sensor readings.

  • Many cam/crank sensors are single-use during timing belt/chain service; ensure correct installation and ECU synchronization after replacement.

bottom of page