P0720 is a generic OBD II trouble code, meaning it has the same meaning for your Oldsmobile Aurora as it does for any other vehicle. Indicates that your Aurora’s OSS (Output Shaft Speed Sensor) is reporting a malfunction. It is usually caused by a faulty OSS, or a wiring problem.
The OSS works by turning a gear at the end of the transmission. As it rotates, the voltage across the OSS changes. This signal is sent to your Aurora’s ECM, which uses it to determine when and how hard to shift gears.
P0720 Fast Data
- Does not affect engine operation
- Usually caused by a faulty output shaft sensor
- Can cause the transmission to shift abruptly
P0720 Symptoms: Oldsmobile Aurora
You should notice symptoms when your Aurora has P0720. Since the code is related to the transmission, your engine should run fine. The concern will be how the transmission behaves without the OSS signal
These are the most common P0720 symptoms:
- Erratic and delayed gear shifting
- Speedometer and/or cruise control do not work
- service engine light
- Bad fuel consumption
In very rare cases, the vehicle may fail or even die when stopping.
Causes of Oldsmobile Aurora P0720
These are the most common causes of P0720:
Gear wear on the OSS
Your Aurora’s OSS works by turning a gear and converting that movement into a signal that the ECM can use. Some makes and models use plastic gear. This gear can wear out over time. What was the speedometer like before the code appeared? Did he move a lot? Did it seem accurate? That’s a good indication that the OSS gears could be compromised. If it has been, you will need to replace the gear to fix the problem.
The output speed sensor itself may be bad. This can occur throughout the life of the vehicle. You will need a multimeter to diagnose it.
Here’s a great video on how to diagnose OSS with a multimeter.
Wiring problems can cause P0720. The OSS wiring is lower to the ground than many cables. It also has a greater distance to travel to the ECM. With these two factors working against it, it is more common for the OSS to have wiring problems related to it than many other parts of the vehicle. An open/short or poor ground will trigger P0720
1. Check the harness connection
Look at where the wiring harness connects to the OSS. Is it corrosion-free? Is it connected well? If not, clean it and replace it if necessary. Wire harness problems are very common when diagnosing this code.
2. Broken and damaged wiring
Check if any part of the wiring harness has been compromised. Look for wires that have been burned or frayed. Anywhere close to the leak is a good place to look.
Transmission fluid temperature sensor
In some vehicles, the OSS is connected to the TFT sensor. If there is a problem with the TFT sensor or the voltage coming from it, it will affect the OSS. This will launch P0720.
P0720 is relatively easy to diagnose. Although it can be a challenge to get to the OSS. Good luck repairing your Oldsmobile Aurora. If there is anything you would like to add, leave a comment below.
See also: P0700