John Deere Fault Code List (Meaning and How to Fix Them)

As you prepare to start your John Deere, you notice a strange code on the screen. The code indicates a problem with the system that should be resolved soon.

So, today I’ll discuss the John Deere codes, their meanings, and solutions.

John Deere has multiple fault codes for different units, such as the Engine Control Unit, BCU, ACU, and TCU, fault codes. While some problems have clear-cut and easy solutions, others need immediate attention and expert assistance. Most issues can be fixed by performing a reset on your John Deere.

John Deere Codes
Image Source: Deere

Now, let’s discuss the John Deere fault codes, their meanings, and how to fix them. 

John Deere Fault Codes: Quick Overview

John Deere has around 20 diagnostic trouble and fault codes. Here is a quick overview of the major fault codes for major control units and their meanings.

Types of Fault Codes Description
ECU Fault Codes Engine Control Unit Fault Codes.
ACU Fault Codes Armrest Control Unit Fault Codes.
BCU Fault Codes Basic Control Unit Fault Codes.
DCU Fault Codes Diagnostic Control Unit Fault Codes.
TCU Fault Codes Transmission Control Unit Fault Codes.
John Deere 6330 Fault Codes
Image Source: Flickr

John Deere 6330 Fault Codes

JD model 6330 is one of the premium tractor models. This particular model has around 70 fault codes from different control units. Here are a few of them.

Fault Codes Description How to Fix
Fault code 02 Forward pedal. The voltage signal is not calibrated and is out-of-range. Add fresh fuel in the fuel tank and add a fuel stabilizer for adjusting the oil flow.
Fault code  08 Throttle sensor. Reduced engine performance due to clogged fuel filter, no anti-stall function. Clean or replace the fuel filter and add sufficient coolant to the radiator.
Fault code  07 Cruise Set/Decel switch. The cruise Set/Decel switch is held or stuck. Inspect the battery and check the terminals and wiring.
Fault code  200 The primary throttle was shorted to a high source.  Check the battery terminals and wiring, and clean dirty radiator fins.
Fault code  201 The fuel pressure sensor output voltage is higher than the normal temperature sensor output voltage. Clean mower deck debris, replace the blades and inspect the engine fuel filter for dirt.
Fault code  205 Problem with engine fuel temperature. Fuel temperature sensors are producing a higher voltage than usual. Connect the hydraulic motor to a 300 Series SCV with a compensator valve to regulate pressure.

John Deere 333E Fault Codes

JD 333E has several fault codes. In general, there are two types of speed sensor errors. Check the table below for the codes and their description and fix.

Fault Codes Description How to Fix
Fault code 1594.02 Left speed sensor. Bad or erratic data. Short or open circuit, faulty sensor wirings. Inspect the circuit and check and replace the faulty wiring.
Fault code 1595.02 Right speed sensor. Bad or erratic data. Bad calibration or faulty sensor wiring. Re-calibrate the sensor and check the sensor wiring for defects. Replace the faulty wirings, if any.

Here’s a complete bonus guide to troubleshooting the 1595.02-speed sensor error.

John Deere ECU Fault Codes

There are more than a hundred diagnostic fault codes of the Engine Control Unit. Below is the most common one people face with John Deere products.

Engine Control Unit Fault Codes Description Solution
ECU 000100.18 Engine oil pressure is low. Check the oil pressure in the engine and add sufficient oil to the tank.
ECU 000110.00 Engine coolant temperature is high. Check the coolant level in the radiator and clean the radiator fins; if the code reappears, get help from a John Deere technical. 
ECU 000110.03ECU 000110.04 Engine system malfunctioned. The engine coolant temperature sensor’s input voltage is incorrect.
ECU 000190.00 The engine speed is high. Check the ignition and cooling system. Reduce fuel supply by adjusting fuel pressure to ideal.
ECU 000627.01 Electronically controlled injectors have voltage problems. Check the injector circuit for open coils and replace the damaged wiring harness.
ECU 000647.05 Fan system malfunctioned. There is a short circuit or an open in the upper output circuit 1 of the fan drive. Ensure the solenoid coil wires above the piston housing of the fan drive are in good condition.
ECU 003510.03ECU 003510.04

ECU 003511.03

ECU 003511.04

ECU 003512.03

ECU 003512.04

ECU 003513.03

ECU 003513.04

The supply voltage in the ECU sensor is malfunctioning.  Check for an open circuit in the solenoid valve of the power supply circuit. Also, check the wiring harness.

How to Retrieve John Deere Engine Codes?

A technician can help you to retrieve the John Deere fault code. However, you can easily retire the John Deere engine fault codes at home. Follow the below steps:

  • Ensure that the ground you select is level and sturdy before parking the machine. It is necessary to retract the boom fully and then level the machine.
  • Keep the parking brake set and the transmission control lever neutral when lowering the boom.
  • Next, start the engine with the ignition on. Now slightly press and hold the reset button on the dashboard for 3-5 seconds. Afterward, the fault lamp will display the error code.
  • You will see the first digit flash by the light after a brief pause to display the second digit.
  • As far as active codes go, the 32 flash codes are at the top of the list. If none are present, 88 codes will flash. It will display code 33 when a defect code recorded is relevant. if there is no stored fault code, 88 will be displayed.
  • After successfully retrieving the code, you should turn off the ignition.

John Deere ACU Fault Codes

Armrest Control Unit Fault Codes Description Solution
ACU 000158.04 Rear PTO malfunction. Low transmission oil, damaged wire, and corroded terminals. Use good transmission oil, check for faulty or damaged wires, and clean the terminals from corrosion.
ACU 000177.17 Transmission fluid is low. Add sufficient fluid to the tank, and reduce engine speed to less than 1500 RPM until the hydraulic oil temperature reaches -5 °C or 23 °F.
ACU 000974.20ACU 000974.21 Hand throttle circuit has a voltage issue or is loosely mounted, a faulty sensor, or there’s an electrical short on the circuit. Inspect the circuit for short, and ensure the connection isn’t loose or the wirings aren’t damaged. Replace the sensor if faulty.
ACU 002000.09 The fuse F24 is faulty. ECU message won’t display. Replace the faulty F24 fuse.
ACU 523955.31 Engine overload when manual mode is selected. Reduce the load or ballast of the vehicle for optimal performance.
ACU 523923.02ACU 523923.03

ACU 523923.04

Problem with the sensor or SCV I control level switch. Troubleshoot the sensor and SCV control switch. Replace the switch if faulty.

In the above table, I’ve mentioned ballasting your tractor. While other fixes are common, many people don’t know what ballasting means. Let me simply explain this.

What is Ballasting a Tractor Mean and Why Is it Important?

Ballasting is the process of maximizing the traction of your tractor. This ensures more friction is created between the tires and the road surface, allowing it to move a heavy trailer with less inertia and friction.

Ballasting increases grip and reduces slippage.

How to Ballast Your Tractor?

There are two types of Ballast procedures available:

  • Metal Ballast: The process of adding metal weights like cast iron on the tractor’s body or the axle or hub of the tractor wheels.
  • Water Ballast: The process of filling the tractor tire with water.

How to Metal Ballast Your Tractor?

When you need to pull or carry a light load with your tractor, you should place most of its weight at the rear.

When carrying a heavy load, the weight should be evenly distributed between the front and rear wheels of the tractor. Check the below table:

Weight Distribution Between the Front and Rear Tires (%)

Type of Tractors Light Load Medium Load Heavy Load
Front Rear Front Rear Front Rear
Two Wheeler 25% 75% 30% 70% 35% 65%
Four Wheeler 35% 65% 35% 65% 40% 60%

*The values are approximate and may vary depending on several factors

How to Water Ballast Your Tractor?

Verify the compatibility of the water ballast with your tractor manufacturer’s guidelines before water ballasting.

To fill the tires with water, position the valve to the top. Now fill the tires with a mixture of water and antifreeze to the valve or up to 34% of its height.

Lastly, adjust the remaining air pressure in the tire using a tire pressure gauge. Since the tires will have less air than usual, you’ll get less shock absorption.

But don’t worry. You can get the help of a technician to adjust the tractor suspension accordingly.

John Deere BCU Fault Codes

Basic Control Unit Fault Codes Description Solution
BCU 000070.31 The handbrake is faulty. Troubleshoot the handbrake and fix the issue.
BCU 000084.02 The circuit is faulty. Inspect the faulty circuit and replace the damaged parts as needed.
BCU 000168.16 The voltage gets too high when the engine is running. Check the voltage regulator and replace it if faulty.
BCU 000168.17  The voltage gets low when the engine reaches 1500 RPM or above. Reduce the engine RPM below 1500, and adjust the voltage accordingly.
BCU 000186.02 Issue with the PTO. Check the PTO circuit and replace the clutch.
BCU 000186.17 Speed of the rear PTO that is not registered. Adjust the rear PTO speed with the help of a technician.
BCU 001676.31 There is a circuit error with the relay for the LTC coolant pump. Inspect the closed circuit and replace the faulty relay.
BCU 000746.31 The differential lock solenoid valve has a circuit issue. Replace the solenoid coil and armatures if needed.
John Deere TCU Fault Codes
Image Source: Farmers Weekly

John Deere TCU Fault Codes

Transmission Control Unit Fault Codes Description Solution
TCU 304020.02 Signal transmission malfunctions. Replace transmission fluids, replace faulty solenoids, fix seals, and adjust the throttle cables.
TCU 304019.05 There is a problem with the clutch pedal sensor. Diagnose the clutch pedal circuit with a multimeter and show the readings to a technician.
TCU 304050.04 There is a grounded circuit for channel 1. Check the circuit in channel one and fix the grounding with the help of a technician.
TCU 304024.04 The grounding of an electrical system has failed. Ensure proper grounding of the electrical systems.
TCU 304032.03 The electrical system has a short circuit. Change the fuse and replace the damaged wires.
TCU 304057.03 Channel one has an open or short circuit. Close the circuit and change or replace the damaged parts.
TCU 304033.03TCU 304040.03 The power circuit is short or has an open circuit. Ensure the circuit resistance is not zero, rewire the circuits, and replace the faulty fuse.

How to Check John Deere Fault Codes?

Hold the roll mode switch for five seconds to begin a diagnostic session. Once in diagnostics, any active or previously active code displays scrolling.

Each will show the control unit (3-letter abbreviation) and the code number (XXXXXXX.XX).

For instance, fault code TCU 304033.03 that’s the format of the code we’ve discussed above. You can view or clear any given codes by following these steps:

  • Scroll to the desired control unit using the right turn signal switch.
  • Enter the diagnostic addresses for the desired control unit by pressing and releasing the roll mode switch.
  • For the desired control unit, use the right turn signal switch to scroll to diagnostic address 001.
  • If the code entered is present, the word “codes” will appear on the screen. The word “none” will be displayed if the code doesn’t exist.
  • You can view all code details for this control unit by pressing and releasing the roll mode switch.
  • Keep scrolling; you’ll find multiple codes appearing if they exist in the control unit.
  • Press and release the right turn signal switch to access the option for clearing codes for this selected control unit.
  • The question “CLR?” will be displayed on the screen.
  • Hold down the roll mode switch and release it to clear the codes.
  • Press and release the left turn signal switch to return to the entire control unit list.

How to Reset the Codes on a John Deere?

The fault code diagnosis and clearing process vary depending on the John Deere model you’re using.

Some tractor models need to activate the hazard switch or disengage the solenoid. Also, you can use the OBD-II scanner to clear the codes.

But clearing the reset code without solving the issue will make the code reappear after a while.

So, contact a John Deere expert or go to the nearest service center for fault code diagnosis or reset. Here’s the procedure to clear the codes on John Deere skid steers. 

How to Clear the Codes on a John Deere Skid Steer?

  • On the monitor, press “MENU” for 5 seconds until “CODES” appears.
  • Select “SELECT” to display engine and machine diagnostic codes.
  • For your records, write down any codes you see in the system
  • Click “SELECT” to scroll through the codes until “END” appears.
  • On the screen, press “SELECT” again, and you will see the message “WAIT”.
  • To clear all John Deere diagnostic codes from the system, hold “SELECT” for at least 5 seconds. If the code reappears, contact a John Deere expert.

What Should I Do If I Receive Fault Codes Again?

The engagement and monitor unit will regenerate the codes if the original problem persists.

That likely means that the repair you completed either wasn’t done correctly or properly but didn’t address the issue after you cleared the codes. 

While some diagnostic codes indicate a clear-cut problem, others require further investigation and a technician’s help.

You can follow the service manual for easy troubleshooting and fixes, but some critical problems need expert attention.


What Do HCU Fault Codes Mean in John Deere?

The HCU stands for ‘Hitch Control Unit Diagnostic Trouble Codes.’ The fault codes will appear if your John Deere tractor system detects a problem with the hitch control system. The most common HCU codes are HCU-000158.04 and HCU-000168.04.

Will Disconnect the Battery Clear Fault Codes?

Yes, disconnecting and reconnecting the battery will reset and restart the system computer. It’s one of the easiest and best methods to clear fault codes. You should leave the battery and disconnect the battery for at least 15 minutes to clear the codes.

What Is the Most Common Failure Of an ECM?

The most common failure of the ECM is a wiring harness. If the transmission wires or the fuel injectors are corroded, it causes malfunction. There are also symptoms such as difficulty starting the vehicle, erratic engine behavior, and reduced engine performance.

The Bottom Line

Thank you for your patience. That was all about your query on john deere codes. I have discussed all the major codes related to ECU, BCU, ACU, and TCU.

One tip from me is always follow the manufacturer’s guidelines while fixing fault codes yourself.

If you have difficulty troubleshooting, go to the nearest John Deere service center or hire a John Deere expert. I will see you in the next write-up. Until next time.

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