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P073F Unable to engage Gear 1

OBD-II Trouble Code Technical Description

Article by
Patrick Cameron
Patrick Cameron
Red Seal Certified Technician

Unable to engage Gear 1

What does that mean?

This is a generic powertrain diagnostic trouble code (DTC) and typically applies to OBD-II vehicles equipped with an automatic transmission. That may include but is not limited to vehicles from Volkswagen, Audi, Nissan, Mazda, Ford, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.

As we drive our vehicles, numerous modules and computers monitor and adjust a vast amount of components and systems in order to make the vehicle's operation seamless and efficient. Among those components and systems, you have 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 driver's demands. Another important part of the whole thing is the TCM (Transmission Control Module), it's main function is to monitor, adjust and correlate different values, speeds, driver's inputs, etc. and to effectively shift the vehicle for you! Given the sheer number of possibilities here, you will want to start, and most likely stick to, the basics here.

Most likely, if you are searching this code, your vehicle isn't going anywhere fast (if anywhere at all!). If you are stuck in a gear or can't engage a gear, it would be a good idea to avoid driving the vehicle, or trying to, until the fault is repaired.

The ECM (Engine Control Module) will illuminate the CEL (Check Engine Light) and log a code P073F when it detects that the automatic transmission is unable to engage gear 1.

Automatic transmission gear indicator:
P073F automatic transmission shift indicator

What is the severity of this DTC?

Moderately-high I would say. These types of codes need to be attended to immediately. Sure, the vehicle may even drive down the street, but you will need to repair this before any further damage occurs. You could literally cost yourself multiple thousands of dollars by neglecting this too long or ignoring the symptoms. Automatic transmissions are extremely intricate designs and need to be maintained properly to keep up a smooth operation.

What are some of the symptoms of the code?

Symptoms of a P073F trouble code may include:

What are some of the common causes of the code?

Causes for this P073F code may include:

What are some P073F troubleshooting steps?

Basic Step #1

Verify the integrity of your ATF (Automatic Transmission Fluid). Using the dipstick (if equipped), check the level of the A/T with the vehicle running and in park. This procedure varies a significant amount between manufacturers. That said, this information can usually be found quite easily with the service manual in the dash or sometimes even printed on the dipstick itself! Make sure the fluid is clean and free from debris. If you do not remember ever doing a transmission service, it would be a good idea to check our records and service your transmission accordingly. You'd probably be surprised how dirty ATF can affect the functionality of your transmission.

Tip: Always check ATF level on flat surface to acquire accurate readings. Make sure to use manufacturer recommended fluid.

Basic Step #2

Any leaks? If your fluid happened to be low, it's probably going somewhere. Check your driveway for any signs of oil stains or puddles. Who knows, this may be your issue. Either way, it's a good idea to address this as well.

Basic Step #3

Check your TCM (Transmission Control Module) for any damage. If it is located on the transmission itself or any other location where it may be subject to the elements, take a look for any signs of water intrusion. This could most definitely cause an issue like this, among possible others. Any signs of corrosion on the housing or connectors is also a good sign of a problem.

Basic Step #4

If everything checks out up to now, depending on your OBD2 scanner's capabilities, you could monitor the gear position and verify the functionality. That being said, it will be easy to tell if your transmission is shifting or not by its mere drivability. Do you have it floored and it accelerates painfully slow? It's probably stuck in a high gear (4,5,6,7). Can you accelerated fast yet the vehicle's speed never goes as fast as you'd like? It's probably stuck in a low gear (1,2,3).

Related P073F DTC Discussions

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