P0720 Code: Symptoms and How to Fix It!

The check engine light illuminating while you drive can indicate a serious problem with your car’s engine. A faulty speedometer and poor fuel economy can make things worse. Since the light gets illuminated for most engine error codes, you will need an OBD-II scanner to determine the exact issue. So, the scanner identifies the car has encountered the P0720 code. But what exactly is it? 

Code P0720 indicates a problem with your car’s output speed sensor circuit. Since this engine error code frequently causes performance issues, you should resolve it immediately. So what causes the P0720 code? How can you fix it? 

Keep reading our article to know in detail about this diagnostic trouble code! 

What does error code P0720 mean? 

A P0720 code indicates a problem with your car’s output speed sensor circuit. This sensor measures the car’s speed and sends info to the transmission, notifying it when to shift gears. This data is critical because it allows the powertrain control module (PCM) to determine when you must shift the gear. 

This information is also useful to the PCM when adjusting the torque converter and displaying the car’s speedometer. The code activates when the output speed sensor stops sending signals to the PCM, or the output sensor’s signals are too inconsistent. 

How serious is the P0720 code? 

In most cases, engine code P0720 does not stop a car from being driven. However, if you don’t repair the code, the effects can worsen and lead to further damage to the transmission. So, repairing your car when the code activates is always best.   

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Can I drive with the P0720 code? 

As we mentioned, the code doesn’t stop you from driving your car. But we recommend avoiding driving your car when it activates. The code can lead to severe drivability issues, and you should avoid driving your car for a long time.  

Doing so will cause severe engine and transmission damage, resulting in excessive repair bills when the transmission gets damaged. If your car shows irregular shifting patterns, you should get it inspected by a qualified technician as soon as possible. 

What causes a P0720 code? 

These are some factors that lead to this engine error code.  

• Defective output shaft speed sensor 
• A defective PCM 
• Corroded or damaged wires, as well as loose connectors 
• Transmission fluid contamination or a lack of transmission fluid 
• Defective engine drivability sensors 
• Faulty shift solenoids  

What are the symptoms of a P0720 code? 

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Your car will have drivability issues when the code activates. And mostly, the check engine light will illuminate. Here are some other signs that can indicate the issue. 

• Faulty speedometer 
• Poor fuel economy 
• Transmission shift gets harder 
• Engine misfiring 
• Engine stalling  

Can I fix the P0720 code myself? 

Resolving this engine error code is complicated as you must determine the exact cause and solve the problem. Mostly you’ll need a mechanic’s help. But suppose you’re sure the issue is with your car’s transmission fluid or the shaft speed sensor. Then, that’s typically something you resolve yourself with the help of a car manual. 

How do I fix code P0720? 

You can change the transmission fluid or replace the output speed sensor.  

Changing the transmission fluid  

• Allow the engine to warm up if it is cold so the fluid can drain more easily. Make sure you park the car on a level surface. Then, turn off the engine. Put a cardboard or protective tarp and a drain pan beneath the transmission to catch the old transmission fluid. 
• Remove the bolts on one side of the transmission pan, ensuring the old fluid flows into the drain pan. Then, remove the bolts on the opposite side. Break the seal on the gasket. Inspect the fluid to ensure there are no metal shavings. 
• Get rid of the old transmission filter and O-ring with care. Then, replace the filter and O-ring. Attach a new gasket to the transmission pan with oil-soluble grease. 
• Add new transmission fluid. Lower the car and then add the suggested amount of transmission fluid to the transmission. Check for leaks after restarting your car. 

Replacing the output speed sensor  

• Make sure you park the car on a level surface and use jack stands to raise the front of the car high enough to get underneath it. To secure the back wheels, use wheel chocks. 
• Locate the output speed sensor, which should be on the transmission’s bottom. This sensor resembles a plug and is linked to an electrical connector. 
• To access the speed sensor, disconnect the electrical connector. Then, using a wrench, loosen and remove the sensor. Replace the sensor with a new one. 

What repairs can fix the P0720 code? 

So, has your car encountered this error code? Then follow these steps to repair it! 

• Replacement of the output speed sensor  
• The replacement of wires or connectors 
• Drain the transmission fluid drain and refill it 
• If faulty, replace the PCM 

How much does it cost to fix the P0720 code? 

The cost of fixing the error code depends on the actual issue. For instance, professional transmission fluid draining and replacement typically cost between $240-$290. Replacing an output speed sensor will most likely cost between $330-$380. The cost of the output speed sensor will vary based on your car’s make and model. It can cost around $265 for the parts for high-end cars. 

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