Technical Description of OBD-II Trouble Code
Inability to engage Reverse
What does that signify?
This is a generic diagnostic trouble code (DTC) related to the powertrain and is commonly found in OBD-II vehicles with automatic transmissions. This includes vehicles from various manufacturers such as Volkswagen, Audi, Nissan, Mazda, Ford, and others. While it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
As we drive our vehicles, numerous modules and computers constantly monitor and adjust various components and systems to ensure smooth and efficient operation. One of these components is the automatic transmission (A/T).
The A/T consists of numerous moving parts, systems, and components that work together to keep the transmission in the appropriate gear based on the driver’s demands. Another crucial part of this system is the Transmission Control Module (TCM), which monitors and adjusts different values, speeds, and driver inputs to shift the vehicle effectively. Given the complexity of this system, it is best to start with the basics when troubleshooting.
If you are searching for this code, it is likely that your vehicle is experiencing difficulty moving or engaging a gear. In such cases, it is advisable to avoid driving the vehicle until the issue is resolved.
The Engine Control Module (ECM) will activate the Check Engine Light (CEL) and store a code P073E when it detects that the automatic transmission is unable to engage reverse.
Automatic transmission gear indicator:
How severe is this DTC?
I would classify it as moderately high. Codes like this should be addressed immediately. While the vehicle may still be drivable, delaying or ignoring the repair could lead to further damage. Automatic transmissions are intricate systems that require proper maintenance to ensure smooth operation.
What are some symptoms of this code?
Some symptoms associated with the P073E trouble code may include:
What are some common causes of this code?
Possible causes for the P073E code may include:
What are some troubleshooting steps for the P073E code?
Basic Step #1
Check the integrity of the Automatic Transmission Fluid (ATF). Use the dipstick (if available) to check the ATF level while the vehicle is running and in park. The procedure for this may vary depending on the manufacturer, but the information can usually be found in the service manual or on the dipstick itself. Ensure that the fluid is clean and free from debris. If you have never serviced the transmission, it would be wise to check your records and service the transmission accordingly. Dirty ATF can significantly affect the functionality of the transmission.
Tip: Always check the ATF level on a flat surface for accurate readings. Use the manufacturer-recommended fluid.
Basic Step #2
Are there any leaks? If the fluid level is low, it is likely that there is a leak. Check your driveway for any signs of oil stains or puddles. Addressing any leaks is important regardless of whether it is the cause of this issue.
Basic Step #3
Inspect the TCM for any damage. If it is located on the transmission or in a location exposed to the elements, look for signs of water intrusion. This can cause issues like the one described, among others. Corrosion on the housing or connectors is also indicative of a problem.
Basic Step #4
If everything checks out so far, use an OBD2 scanner to monitor the gear position and verify its functionality. However, the drivability of the vehicle will also provide clues about whether the transmission is shifting properly. For example, if you press the accelerator and the vehicle accelerates slowly, it may be stuck in a high gear (4, 5, 6, 7). If the vehicle’s speed does not increase as expected despite rapid acceleration, it may be stuck in a low gear (1, 2, 3).
