What Does Engine Code P Zero Seven Two Zero Mean?

Code P0720 is one of the OBD codes that is activated when the Powertrain Control Module (PCM) detects erratic or insufficient input from the output shaft sensor (OSS). Such a code generally indicates transmission-related problems and points toward performance issues.

The error occurs because of three components: ECM, PCM, and TCM. The Engine Control Module, or ECM, directly controls the engine. Still, it can’t do that properly without the Transmission Control Module or TCM and PCM, which work together and exchange information. If there’s a miscommunication, you’ll get a Diagnostic Trouble Code (DTC), one of which may be the P0720. 

If you saw the code and are wondering what went wrong, the article will comprehensively answer this question.

Meaning Of Code P0720

The OBD scanner shows the code P0720 when the PCM detects an Output Speed Sensor Service malfunction. If there is a problem with the output shaft or the circuit, or the engine and input shaft speed are at an RPM that is not in sync with the output shaft speed, the vehicle’s computer stores the error code P0720. 

A few things can trigger its appearance, such as:

• Malfunction in the PCM
• Issues with the electrical wiring
• Malfunctioning output shaft speed sensor
• Old transmission fluid

However, along with the code also come car-related issues. They can include a couple of symptoms:

• Issues with gear shifting. If there is a delayed or no gear shift, there might be an issue with the output control shaft. 
• Speedometer malfunctioning. The speed readings will be incorrect, and cruise control might malfunction, possibly proving fatal to the driver and the passengers. 

Can I Fix The Problem Myself?

Addressing the P0720 is no small task, as first, you must diagnose the exact cause and, only then, solve the problem. Most of the time, you’d want to delegate it to a mechanic. But if you’re sure it’s either your transmission fluid or the shaft speed sensor, that’s generally something you can pull off yourself, albeit while consulting with the automobile manual.

Changing The Transmission Fluid

Changing the fluid is a relatively uncomplicated procedure, which you can do by following these steps:

• Warm up the engine. It will help the old fluid drain better and ease the process.

• Park on an even surface and elevate the vehicle. Just like the previous step, it will help the fluid flow better. To elevate the car, use jack stands or a lift, and secure the back wheels with chocks.

• Locate the transmission fluid pan. Get underneath the vehicle, and find the pan that’s located to the engine bay's left or right. It should be attached to the transmission with 6-8 bolts. Check for a drain plug and if there isn’t one, take note that you must remove the whole pan to get the old fluid out.

• Put a cover underneath the pan. A protective tarp, cardboard, or drain pan will help reduce the mess and spillage. 

• Drain the old transmission fluid. Make sure to put on gloves and glasses, and drain the fluid from the plug or by removing the pan entirely.

• Inspect the filter. No matter the method used for draining, remove the fluid pan and locate the filter. Look for any signs of damage, like cracks or leaks, and replace them if necessary.

• Put the fluid pan back. Now put it back on, and make sure not to overtighten the bolts.

• Lower the car and refill with the new transmission fluid. After lowering the car, open up the hood and look for the transmission fluid port, usually distinguished by a red dipstick. Pour the liquid in through a funnel to avoid spillage.

• Check for leaks. Put a different cover underneath the vehicle, and let it run for a couple of minutes to ensure no leaks. If you’ll notice spillage, inspect the fluid pan again and tighten it correctly or replace the pan gasket. If the problem persists, consider replacing the entire pan.

Replacing An Output Speed Sensor

As with the transmission fluid, park the car on an even surface and elevate it. Secure the back wheels with chocks, and go underneath the automobile. Then locate the sensor, which should look like a plug and be at the transmission’s bottom, close to its electrical connector. Disconnect the connector, use a wrench to loosen and remove the old sensor, and then simply install the new one.

Summary

The P0720 code indicates a problem with the output speed sensor, which doesn’t function properly for a few reasons. These reasons may include the sensor itself and things like old transmission fluid, bad electrical wiring, or a PCM malfunction. Unless you’re confident in your car maintenance abilities, delegate the fixing to a qualified mechanic. But, if you think it’s either the fluid or the sensor, consult the manual first and then follow the guides in the article. 

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