Skip the auto shop - Our mechanics make house calls

P2779 OBD-II Trouble Code: Downshift Switch Circuit Range/Performance

check engine light

P2779 code definition

P2779 Trouble Code is for the downshift switch circuit range and performance, and it sets when the voltage or resistance signal is not within the specified range provided by the manufacturer.

What the P2779 code means

The code means there is an issue with the downshift switch. Only vehicles that have manually shifting automatic transmissions will have this code appear. In some instances, it will take multiple failure cycles before this code causes the malfunction light to come on in the vehicle.

What causes the P2779 code?

The following are some of the most common causes of the P2779 code:

  • Liquids being spilled on the upshift/downshift switch

  • Wiring and connector issues – damaged, corroded, shorted, or disconnected connectors or wiring

What are the symptoms of the P2779 code?

In many cases, the symptoms will be very limited, and many drivers may not notice any issues with their vehicles. They will find that the manual shifter function of the vehicle is not working, or that it places the transmission in limp-home mode. If this happens, it will be much easier to realize something is wrong with the vehicle. The vehicle will have a hard time shifting, for example.

How does a mechanic diagnose the P2779 code?

To diagnose the P2779 code, the mechanic will want to connect their OBD-II scanner to the vehicle’s onboard computer. This computer gathers data about the car, and it makes it possible to share that data with the scanner. Naturally, this will make diagnosing the problem with the vehicle much easier. The mechanic will also reset the vehicle and drive it. They do this to see whether the code returns or not. When the code returns, they know that it is something that is actually wrong with the vehicle and it was not triggered by mistake. They can then start their diagnosis on that particular issue.

Common mistakes when diagnosing the P2779 code

One of the biggest mistakes when diagnosing the P2779 code is forgetting that the most common reason for the problem is spilling liquid onto the upshift/downshift switch. Instead of addressing this issue, they believe that the transmission wiring has malfunctioned instead. It is important to look at the most likely cause when diagnosing and repairing vehicles.

How serious is the P2779 code?

It is always important to take your vehicle to a mechanic for regular tune-ups as well as when there is an issue with your vehicle. This is true even if your vehicle still seems to be running well. If you find that there are codes stored in the vehicle, you want to get them diagnosed and taken care of right away. While the P2779 code might not seem too serious, it has the potential to cause some issues with your ability to shift properly. That’s not something you want to deal with.

What repairs can fix the P2779 code?

The following are some of the repairs that mechanics might use when they repair the P2779 code:

  • Check the upshift/downshift switch for damage caused by liquids and repair or replace it.

  • Check the wiring for corrosion, shorts, and bad connections and repair as needed.

  • Replace the powertrain control module

Additional comments for consideration regarding the P2779 code

Keep in mind that it is very rare for the powertrain control module to be at fault in these cases. It is usually the result of spilling liquid on the upshift/downshift switch. If you have noticed any issues with your vehicle, or if you know that you have the code stored in your vehicle, don’t wait on getting it repaired. Even though it might not be causing you any issues when you are driving now, you don’t want to have the problem get worse. Take your vehicle to a mechanic as quickly as possible to get the repairs the vehicle needs.

Need help with a P2779 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
Icon-warranty_badge-02

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

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.

GET A QUOTE

More related articles

Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P0359 OBD-II Trouble Code: Ignition Coil I Primary/Secondary Circuit Malfunction
P0359 code definition The P0359 code indicates that a fault has been detected in one of the vehicle’s ignition coils, generally the number 9 coil. This code can also be associated...


Related questions

Q: I changed out the camshaft position sensor, the car is still stalling and hard to start. It now shows a different P code.

The coolant temperature sensor (CTS) in your vehicle has failed and is making the computer think that the engine is too hot. When you shut off the engine and the engine will not restart, is it because the computer thinks...

Q: What exactly does the code P3fff mean?

Hi there. The code P3fff means that there is an issue with the PCM (the computer to the vehicle). The codes regarding gas recirculation flow and mass air flow are coming on either due to the PCM failure or due...

Q: P1404 check engine code showing and EGR pintle is .5

Hello. Most of the time this is caused by a bad EGR valve. I usually remove the valve and inspect the ports for the EGR valve. If these ports are clogged then the problem will persist. It is possible that...