How to Fix the P0735 Code on Duramax (Step-by-Step Guide)

Would you like to hear about an unpleasant experience? Imagine going on a long drive on your Duramax when suddenly an error code pops up on your display. This kills the mood of the drive.

The code P0735 mean on Duramax primarily refers to an irregular ratio of the 5th gear or the slipping on the 5th gear. Moreover, it indicates a problem with the ECU, which monitors such conditions.

Hopefully, we’ve managed to make your unpleasant experience slightly less unpleasant. But hold your thoughts as there’s more to it. We’ll be discussing the ins and outs of this code, which you might not want to miss.

P0735 Code On Duramax

What Does the P0735 Code Mean on Duramax?

Since code P0735 suggests a problem with shifting the 5th gear, such issues have several drawbacks. This reduces the economic benefits you could have had from your Duramax. Hence, let’s see the breakdown.

  • P= Powertrain, it’s just the collection of components that help propel the vehicle forward.
  • 0= This is a generic number given by the SAE standards.
  • 7= transmission
  • 35= This represents the specific fault index, such as the problem in shifting to 5th gear, as in our case.

This tells us that there is a fault in the transmission or the gearbox, gradually resulting in the 5th gear’s incorrect ratio.

How Serious Is The P0735 Code On Duramax?

The breakdown of this code suggests that the issue isn’t that big of a problem if ignored, and most drivers wouldn’t even mind if this problem persists.

You’re not wrong if you feel that way as well. This issue doesn’t sound that severe, as not everyone requires or fathoms the 5th gear. But before that, do we know what the 5th gear does?

The 5th gear stands for “overdrive” and is responsible for driving at increased speeds without needing greater acceleration. This is more economical and reduces fuel consumption significantly.

So if the 5th gear isn’t working for you, you can reach higher speeds without experiencing higher acceleration on the freeways. Needing more acceleration puts stress on the engine and increases fuel usage.

You will not only get lower fuel mileage but also age your Duramax faster if you keep pressing the accelerator pedal frequently. Hence, it might be harmful to people who drive on the freeways.

What Causes The P0735 Code On Duramax?

So far, you’ve encountered the reason for seeing this code on Duramax. But several other more minor causes may also lead to this problem in the long run. Hence, let’s learn about those causes!

  • Very low and contaminated transmission fluid.
  • There is an internal blockage in the transmission control.
  • The problems with the shift solenoids.
  • The transmission is suffering from technical problems.
  • Problems with the hydraulic control circuit.
  • The gearbox has some issues.
  • The ECU is damaged.

How To Fix The P0735 Code On Duramax?

There are quite a few ways to resolve this issue for good. However, it’s challenging to find the correct combinations of diagnoses that can help fix this issue. Hence, we’ve given you the steps you might need to fix the problem.

Step 1: Diagnose The Code To Check If The Code Exists

There might be two possible systems that may lead to this code. This could be the electrical or hydraulic system. If the damaged components are related to solenoids, then that might be simpler to fix.

However, if the problem lies within the hydraulic system, a torque converter stall test must be performed to confirm the problem’s existence.

Step 2: Check The Transmission Filter And Fluid Levels

Ensure that your Duramax’s transmission is performing at the optimum level. Since this code heavily relies on the problems in shifting to the 5th gear, checking the transmission fluid level might be a good idea.

If you notice reasonable amounts of transmission fluid, it might be a good idea to check if the transmission filters are clogged. Unclog or replace the filter if required.

Step 3: Check For Damaged Connections

One other thing that can lead to this issue is a faulty wiring circuit. Hence, you must conduct a thorough investigation to check for any damaged connections. If you spot any, immediately repair or replace the wires.

Step 4: Ensure That The Transmission Is Working Fine

There might be a few cases where the transmission faults some components. A failed transmission could cause this code to show up on your Duramax.

However, the problem seems to persist from a faulty torque converter component. This calls for immediate replacement of the defective parts. Moreover, if the ECU is at fault, consider replacing that too.

Other Symptoms Of Getting P0735 Code On Duramax

You must have a basic idea about some important symptoms that might come up with this code. Otherwise, you wouldn’t be able to tell the condition of your Duramax. So let’s look these up!

  • The slipping of the gear.
  • The check engine light glows up.
  • The shift pattern becomes inconsistent.
  • It’s difficult to engage the 5th gear
  • Engine stalling has become common.
  • The fuel consumption increases significantly.
  • The engine’s peak performance decreases quicker in the long run.

How Much Does It Cost To Fix The Duramax P0735 Code?

The cost of fixing your P0735 code on your Duramax depends on several factors. It depends on the component that requires fixing and the location, as different local stores have different charges.

Hence, if you don’t want to go through the hassle of doing the entire diagnosis process yourself, you might want to invest in a mechanic who may cost you somewhere between $75 and $130.

Moreover, if you consider doing the resolving part on your own, you can save up the added labor cost and would only have to pay for the specific role that requires replacement, which is something as mere as a wire.

Can You Drive Your Duramax With Code P0735?

It’s not as wise of a choice to take your Duramax on the road with this code showing up on it. However, as dumb as it may sound, you can easily take this ride to the roads as you don’t always need the 5th gear.

But remember that this would significantly increase your fuel consumption and cause your engine to age more quickly due to the increased rate of higher acceleration.


Throughout this entire piece of writing, we’ve been trying to convey the importance of this fault code and the possible implications of the solutions. Hopefully, we’ve been able to reach you through.

A vehicle with an error code is like a patient with a sickness that slowly destroys every healthy component of the body if left untreated and neglected.

Hence, it’s your responsibility to care for your Duramax and its needs. And this article has everything you’ll need regarding this code. So you can let yourself rest for a while, even after you notice this code P0735.

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