What does it mean?
This is a generic diagnostic trouble code (DTC) for the powertrain and generally applies to OBD-II equipped vehicles with automatic transmissions. This may include, but is not limited to, vehicles from Volkswagen, Audi, Nissan, Mazda, Ford, etc. Although generic, the exact repair steps can vary depending on the year, make, model, and powertrain configuration. As a side note, this code is more commonly seen on VW and Audi vehicles.
As we drive our vehicles, many modules and computers monitor and adjust a large number of components and systems to make the vehicle’s operation smooth and efficient. Among these components and systems is the automatic transmission (A/T).
Within the A/T alone, there are countless moving parts, systems, components, etc., to keep the transmission in the correct gear according to the driver’s demands. The TCM (Transmission Control Module) is another important part of the setup; its main function is to monitor, adjust, and correlate different values, speeds, driver inputs, etc., and efficiently move the vehicle for you! Given the vast number of possibilities here, you’ll want to start, and probably stick to, the basics.
Most likely, if you’re looking up this code, your vehicle isn’t going anywhere fast (or even anywhere at all!). If you’re stuck in a gear or in neutral, it would be a good idea to avoid driving the vehicle, or trying to, until the issue is fixed. Let’s say you’re stuck in second gear and try to reach highway speeds; you might get it over 60 km/h. That said, your engine will be working extremely hard to maintain the desired speed. Engine damage is very likely in these situations.
The ECM (Engine Control Module) will turn on the CEL (Check Engine Light) and record a P073B code when it detects that the automatic transmission is stuck in 6th gear.
How severe is this DTC?
Moderately high, I’d say. These types of codes need to be addressed immediately. Of course, the vehicle might even drive on the street, but you’ll need to fix it before further damage occurs. You could literally cost yourself thousands of dollars by neglecting this for too long or ignoring the symptoms. Automatic transmissions are extremely complex designs and need to be properly maintained to ensure good operation.
What are some of the symptoms of the code?
Symptoms of a P073B trouble code may include:
- Abnormal vehicle speeds
- Weak battery
- Abnormal engine noises
- Reduced throttle response
- Limited vehicle speeds
- ATF (Automatic Transmission Fluid) leak (red fluid under the vehicle)
What are some common causes of the code?
Causes of this P073B code may include:
- Blockage in transmission hydraulics
- Low fluid level
- Dirty fluid
- Incorrect fluid
- Shift solenoid issue
- TCM problem
- Wiring issue (e.g., chafing, melting, short, open, etc.)
- Connector issue (e.g., melting, broken tabs, corroded pins, etc.)
What are the troubleshooting steps for P073B?
Basic Step #1
Check the integrity of your ATF (Automatic Transmission Fluid). Using the dipstick (if applicable), check the fluid level with the vehicle running and in park. This procedure varies significantly from one manufacturer to another. That said, this information can usually be found quite easily in the service manual in the glove box or sometimes even printed on the dipstick itself! Make sure the fluid is clean and free of debris. If you don’t remember ever having transmission service done, it would be a good idea to check your records and service your transmission accordingly. You’d probably be surprised how much dirty ATF can affect your transmission’s functionality.
Tip: Always check the fluid level on a level surface for accurate readings. Be sure to use the manufacturer-recommended fluid.
Basic Step #2
Any leaks? If your fluid was low, it probably went somewhere. Check your driveway for any signs of oil stains or puddles. Who knows, that might be your problem. In any case, it’s a good idea to address this issue as well.
Basic Step #3
Check your TCM (Transmission Control Module) for any damage. If it’s located on the transmission itself or anywhere else where it might be exposed to the elements, look for any signs of water intrusion. This could very well cause a problem like this, among other possible issues. Any sign of corrosion on the housing or connectors is also a good indicator of a problem.
Basic Step #4
If everything checks out so far, depending on your OBD2 scanner’s capabilities, you can monitor the gear position and check functionality. That said, it will be easy to tell if your transmission is shifting or not by its drivability alone. Do you floor it and it accelerates painfully slowly? It’s probably stuck in a higher gear (4,5,6,7). Can you accelerate quickly, but the vehicle speed never goes as fast as you’d expect? It’s probably stuck in a lower gear (1,2,3).