P0735 OBD-II Trouble Code: Gear 5 Incorrect Ratio

P0735 code definition

The P0735 code is an indicator that the automatic transmission can’t be shifted to the 5th gear.

What the P0735 code means

This code is used in vehicles that are built with automatic transmissions/transaxles that rely on torque converters to drive the rear wheels and increase the engine torque output. The converter is located between the transmission and the engine. Most modern vehicles are equipped with this type of transmission setup.

P0735 can be triggered when your vehicle is driving in 5th gear or while you’re shifting into it. With an automatic transmission, the vehicle’s computer is in charge of the shifting. Part of the process involved is calculating engine speed against the transmission speed sensor to assess the torque converter slip and gear ratio.

If the calculation doesn’t match the ideal value, the P0735 code will show and the Check Engine Light will come on. The code is also associated with P0730, P0731, P0732, P0733, P0734, and P0736. These codes should be addressed first before proceeding with trying to fix the problems behind P0735.

What causes the P0735 code?

There are a handful of common reasons the calculation we mentioned above may not match up and thus cause a P0735 code. These are:

• The transmission fluid is low or dirty
• The transmission main control is suffering from internal blockage
• Shift solenoids
• Transmission hydraulic control circuit
• Mechanical problems inside the transmission

What are the symptoms of the P0735 code?

One very common symptom would simply be the Check Engine Light coming on. A more specific one, though, would be if you notice that the transmission is shifting incorrectly. Your vehicle may not even be able to hit 5th gear. Either case would indicate that the components responsible for automatically doing this for you are experiencing some type of problem. You may also even be able to feel the transmission slipping. Finally, a loss of fuel economy is also a potential symptom related to P0735.

How does a mechanic diagnose the P0735 code?

As we mentioned above, a mechanic would first address any other codes. Then, the mechanic would check the fluid level and then its condition – whether it’s dirty or not. They may also test drive the car quickly if it’s only displaying one incorrect ratio code. This will show them if the gear is actually working or not.

As the internal clutches of a transmission are usually controlled by fluid pressure or a solenoid, a mechanic would check there next. They’d also want to see if a fluid passage is being obstructed in any way. A mechanical issue could also be to blame. Examples would be issues with the transmission main control, or torque converter.

Common mistakes when diagnosing the P0735 code

A lot of times, all a mechanic needs to do is address internal transmission failures as this is responsible for the P0735 code more often than not. Unfortunately, many mechanics will miss this completely and replace a solenoid unnecessarily.

How serious is the P0735 code?

Best case scenario, a P0735 code means you’re not getting the fuel economy you should and you’re going to have a difficult time accelerating. On the other hand, the underlying issue causing your shifting problems could also be a symptom of something far more serious. You could end up with an overheated transmission or otherwise needing to replace yours.

What repairs can fix the P0735 code?

• The first thing that’s necessary to do is check the vehicle’s transmission fluid in terms of its condition and whether or not it has sufficient pressure.
• If the fluid has been burned, the transmission pan needs to be removed and inspected for signs of clutch material and other debris
  
• The circuitry and connectors will also need to be inspected and replaced if necessary.

Additional comments for consideration regarding the P0735 code

Even after repairs and after the system has been retested, use a short test-drive to ensure shifting works and to see if P0735 or other associated codes return. Also, if an intermittent issue is to blame, it’s going to take a lot more work to pin down the problem. The mechanic should look at every possibility before blaming PCM failure as this is extremely rare and a costly piece to replace.

Need help with a P0735 code?

If any of the above sounds familiar, YourMechanic is here to help. To speak with a service advisor, call 1-800-701-6320. You can also schedule an appointment online with one of our certified mobile mechanics. Either way, you’ll receive a free quote and the mechanic will meet you at your home or place of business.