Skip the auto shop - Our mechanics make house calls

P0873 OBD-II Trouble Code: Transmission Fluid Pressure Sensor/Switch C Circuit High

Check Engine Light

P0873 code definition

The P0873 trouble code refers to a detected anomaly in the transmission fluid pressure. The reported pressure has fallen beyond the manufacturer's set parameters.

What the P0873 code means

The vehicle's Powertrain Control Module (PCM) is fed information on many aspects of the vehicle's systems, including transmission fluid pressure. In a P0873, the sensor in the transmission system's C circuit has detected a pressure level that extends beyond the manufacturer's set limits.

What causes the P0873 code?

A P0873 is most often caused by a problematic transmission system.

  • Dirty, contaminated or burnt transmission fluid is the most common cause
  • Mechanical problems with the transmission system
  • A faulty or damaged transmission system
  • Faulty sensor or overheated engine

In very rare cases, the PCM itself may be faulty and reporting false information. Because PCMs are notoriously difficult to repair or reprogram, this slight possibility should only be considered if all other possible causes have been exhausted completely.

What are the symptoms of the P0873 code?

A P0873 scenario typically involves problems with the transmission. When the vehicle is being used, there will usually be a distinct smell of burnt transmission fluid, as well as smoke possibly emanating from the transmission system. Practical concerns regarding the transmission system, including gear slippage, are also possible. For the sake of identifying and diagnosing the issue, the P0873 code and dashboard trouble lamp will be activated to alert the operator.

How does a mechanic diagnose the P0873 code?

The P0873 trouble code may be first diagnosed by uplinking to the vehicle's onboard computer with an OBD-II code reader. The components related to the transmission system (including the sensor that picked up the issue) should be thoroughly inspected for signs of wear. If a leak has been detected at some part of the transmission system's body, a visual mark of it should be made for reference during the repair stage.

Common mistakes when diagnosing the P0873 code

Technicians have reported the P0873 code cause to be underestimated and mistakenly blamed on bad transmission fluid. Instead, the primary cause (a faulty transmission pump, for instance) may have subsequently resulted in fluid issues.

How serious is the P0873 code?

A P0873 trouble code suggests there are serious issues with the transmission system. Because of this, it is not recommended using the car until the transmission system has been checked thoroughly and addressed accordingly.

What repairs can fix the P0873 code?

  • If any components in the transmission system (including the sensor itself) have been identified as faulty, they should be repaired or replaced outright

  • Leaky segments in the transmission system should be patched up and repaired

  • Any corroded, broken or faulty wiring related to the transmission system, including connectors, should be repaired accordingly

  • Following your set of repairs, the vehicle should be test-driven immediately. Giving the vehicle a few minutes of use will allow you to see whether or not the code has been solved

  • In the rare instance that the PCM itself may be faulty, it will need to be repaired and reprogrammed, or replaced outright

Due to the expensive and long time it takes to commit to PCM repairs, this option should only be pursued if it's made absolutely clear that the PCM is at fault.

Additional comments for consideration regarding the P0873 code

The particular pressure limits needed to trigger a P0873 code will vary depending on the model and manufacturer of the vehicle.

Need help with a P0873 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701- 6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
The Traveler’s Guide to Driving in Malaysia
CraigBurrows / Malaysia is a popular destination for many tourists today. The country has amazing sights and attractions that you will want to explore....
How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...

Related questions

Q: Check engine light flashing, sucking fuel, procrastinating when accelerating...

This is a very odd set of symptoms. I would suggest ruling out any fuel-related issues as the poor fuel economy and lack of power could be related to faulty sensors like the throttle body sensor, mass air flow sensor,...

Q: Need to know if I should replace my turbo or not

Hi, thanks for writing in. The turbo system is comprised of several different components. Without knowing the exact trouble code, it would be hard to guess at what is going on. There could be a bad sensor, a leaking intake...

Q: 1999 firebird every now and then dies while driving and low engine power light comes on

A bad mass airflow (MAF) sensor can cause loss of power, no starts, and lean or rich conditions. If cleaning the sensor did not get rid of the P0102 trouble code, then replace the MAF sensor and clear the...