DIY Car Fix: Signs Of A Bad Engine Speed Sensor

Your engine speed sensor helps your vehicle's computer determine how fast the engine is spinning. It does this by sensing the crankshaft's speed. But, just like other components, this sensor may go bad. The following guide will help you detect a bad sensor and help you replace it.

Signs Of A Bad Engine Speed Sensor

The following are some signs to look for:

  • Your transmission will rev higher every time you change gears
  • Engaging your overdrive will either be delayed or will not happen at all
  • Your brakes may feel harder, especially when you are simply coasting
  • The speedometer will behave strangely or not work at all
  • Check engine light may turn on and off when accelerating
  • Overdrive light might switch on and off periodically as well

The problem may lie with your engine speed sensor if you notice the aforementioned symptoms. You can talk to your auto care specialist if you want to make sure your suspicions are correct. If you decide to take on the task, the following instructions will help you.

How To Replace Your Own Engine Speed Sensor

You will need the following:

  • A new vehicle or engine speed sensor that is specific to your car
  • Your jack
  • Jack stands
  • Your socket wrench set
  • Your owner's manual
  • Gloves and goggles for your protection


  1. Park your vehicle on level ground, and make sure your work area is safe.
  2. Let your car rest long enough to cool down so that you can work on it.
  3. Disconnect your battery, just for your own protection.
  4. Jack your vehicle up in the front, as your sensor is usually located right under your transmission.
  5. Use your jack stands to secure your vehicle in place.
  6. Locate the sensor using your owner's manual.
  7. The sensor will look like a small plug with an electrical cord; it will be near the transmission body.
  8. Now remove this electrical plug. Just apply a little pressure on the plug, and carefully release the grip.
  9. Use your wrench to unscrew the sensor in a counter clockwise motion. Make sure you do so carefully and without applying too much pressure. You do not want the sensor to break in the threads.
  10. Use a rag to clean the threads, and then replace with your new sensor. Use your hand to screw it into place. Use your wrench once the sensor is too tight for your hand. All you have to do is screw it in a few times with your wrench.
  11. Wipe the connector, and reconnect the cord to your new sensor.
  12. Lower your car, and reconnect your car battery.

This should have taken care of your little issue. But do not hesitate to talk to your auto care specialist if the problem persists as it could be related to your transmission. (for more information, contact Dave's Import Repair or another company)