How to Read John Deere Fault Codes (2026 Update)
Modern heavy machinery requires detailed diagnostic tools to monitor performance and detect potential issues. John Deere fault codes offer a reliable way to troubleshoot machinery faults. However, the challenge that arises is understanding the meaning of these codes.
John Deere tractors, harvesters, and other agricultural machines rely on advanced onboard diagnostic systems to monitor engine performance and machine health. When a problem is detected, the system generates John Deere fault codes that help technicians quickly identify the issue.
Understanding how to read these John Deere diagnostic codes can save operators time, prevent costly breakdowns, and reduce equipment downtime. In this guide, we’ll explain how John Deere fault codes work, how to read them, and how to diagnose the underlying problems.
In this article, we will discuss how to read John Deere fault codes, what they mean, and how to troubleshoot and resolve them.
Understanding John Deere Fault Codes
John Deere machines have an onboard computer known as the Engine Control Unit (ECU). The ECU monitors and controls several components in the machine. When the computer detects a problem with any component, it generates a fault code to alert the operator. Users can only find these codes by using a diagnostic scanner that interfaces with the ECU.
When a fault code is displayed on the machine's monitor, it will consist of a series of letters and numbers. Here is an example of a typical fault code: "ECU 001509.07". Let's break down what each part of the code means:
"ECU" - This indicates the system that the fault is related to. The ECU is the vehicle’s electronic control unit.
"001509" - This is the code number that corresponds to the specific fault. This is a unique section of your fault code that differentiates it from other fault codes.
".07" - This is the severity level of the fault. .07 is a less severe fault.
Other fault codes include ACU (armrest control unit), BCU (basic control unit), DCU (diagnostic control unit), and TCU (transmission control unit).
How to Check John Deere Fault Codes
To access the fault codes, you'll need a diagnostic scanner that has the ability to read John Deere fault codes. You can purchase a Jaltest AGV scanner from Wholefleet!
Jaltest AGV is a powerful tool that monitors your John Deere’s engine, transmission, braking, electrical, suspension, and fuel systems. With Jaltest, technicians are able to diagnose, evaluate, and solve problems in their agricultural vehicles with ease.
Once you have a scanner, connect it to the machine's diagnostic port and follow the instructions that come with the scanner.
Watch this video to learn how to perform John Deere 4045 engine diagnostics using Jaltest
Common John Deere Fault Codes and their Meanings
Here are some of the most common John Deere fault codes and their meanings.
Common John Deere Engine Fault Codes
| SPN Code | Component | Common FMI | Description |
|---|---|---|---|
| 100 | Engine Oil Pressure | 18 | Oil pressure signal moderately low |
| 101 | Crankcase Pressure | 0-4 | Crankcase pressure sensor abnormal signal |
| 102 | Manifold Air Pressure | 3 | Signal out of range high |
| 103 | Turbocharger Speed | 9 | Communication lost with turbo speed sensor |
| 190 | Engine Speed | 0-3 | Engine speed sensor abnormal reading |
| 191 | Engine/Pump Speed | 2 | Invalid engine or pump speed signal |
| 636 | Camshaft Position Sensor | 8 | Camshaft position signal missing |
| 637 | Crankshaft Position Sensor | 8 | Crankshaft position signal missing |
| 1136 | ECU Temperature | 0-3 | ECU temperature sensor abnormal reading |
Common John Deere Fuel System Fault Codes
| SPN Code | Component | Common FMI | Description |
|---|---|---|---|
| 94 | Low Pressure Fuel | 7 | Fuel pressure mismatch detected |
| 157 | Fuel Rail Pressure | 0-4 | Fuel rail pressure outside normal operating range |
| 174 | Fuel Temperature | 3 | Fuel temperature signal out of range |
| 632 | Fuel Shutoff Valve | 4 | Fuel shutoff valve circuit low voltage |
| 1075 | Low Pressure Fuel Pump | 31 | Fuel pump operating condition exists |
| 1347 | Suction Control Valve | 5 | High resistance in valve circuit |
| 1348 | Fuel Pump Control Valve | 3 | Valve signal out of range high |
| 1349 | Redundant Fuel Rail Pressure | 2 | Invalid redundant fuel pressure signal |
Common John Deere Air Intake & Turbo System Fault Codes
| SPN Code | Component | Common FMI | Description |
|---|---|---|---|
| 107 | Air Filter Differential Pressure | 14 | Incorrect air filter pressure reading |
| 108 | Barometric Pressure | 3 | Pressure signal out of range |
| 1176 | Intake Air Pressure | 4 | Intake pressure signal too low |
| 1209 | Exhaust Manifold Pressure | 3 | Exhaust pressure signal high |
| 641 | VGT Actuator | 5 | High resistance detected in turbo actuator circuit |
Common John Deere Aftertreatment & DPF Fault Codes
| SPN Code | Component | Common FMI | Description |
|---|---|---|---|
| 3246 | DPF Outlet Temperature | 0-3 | DPF outlet temperature sensor abnormal reading |
| 3251 | DPF Differential Pressure | 0 | Extremely high pressure across DPF |
| 3711 | DOC Inlet Temperature | 0-3 | DOC inlet temperature abnormal |
| 3719 | Calculated Soot Level | 31 | Soot level high in DPF |
| 3720 | Calculated Ash Level | 31 | Ash buildup detected in DPF |
| 4795 | DPF Missing | 31 | Diesel particulate filter not detected |
Common John Deere Electrical & ECU Fault Codes
| SPN Code | Component | Common FMI | Description |
|---|---|---|---|
| 158 | ECU Power Down | 9 | Loss of ECU communication |
| 168 | Battery Voltage | 1 | Battery voltage extremely low |
| 620 | Sensor Supply Voltage | 3 | Sensor voltage out of range |
| 628 | ECU Programming | 2 | ECU programming invalid |
| 629 | ECU EEPROM | 12 | Internal ECU memory error |
| 639 | CAN Bus | 9 | Loss of communication on CAN network |
Troubleshooting and Resolving John Deere Fault Codes
The Electronic Control Unit detects and stores faults in the John Deere’s components. Using Jaltest, you can both obtain and decode the fault code to understand what it means and how to solve the problem. It's necessary to perform a diagnostic test to identify the root cause of the issue. Once the problem has been identified, it's time to fix it. Repairs can either be carried out by a technician or an experienced operator. In some cases, a simple fix, such as restarting the machine, can resolve the issue.
Preventing John Deere Fault Codes
Preventative maintenance is key to avoiding John Deere fault codes. This means performing timely servicing, as specified by the equipment manufacturer. It also involves inspecting and replacing worn out parts and sensors as soon as they are identified.
Frequently Asked Questions
Is it OK to clear John Deere fault codes?
Yes. It is perfectly fine to clear John Deere fault codes. Fault codes don’t always clear automatically, so clearing the fault code is an important part of the troubleshooting process. Clear the fault codes as you troubleshoot your John Deere to see if the code appears again. If the same fault code reappears, that indicates that more troubleshooting is needed.
Will a John Deere fault code clear itself?
The John Deere fault codes are supposed to clear themselves after proper troubleshooting and multiple drive cycles. There may be instances where the code remains however, in which case, you can clear the code manually. You’ll know that the issue is persisting if the same fault code reappears.
Can I read John Deere fault codes without a scanner?
Yes, for most John Deere makes and models, it is possible to read fault codes without a scanner through the built-in diagnostic display on the system’s monitor. However, you’ll need to still follow a precise set of actions to get fault codes to show there. The steps depend on the type of John Deere vehicle it is, but here are some common ones:
For John Deere E Series: Find the button on the left side of the steering column. Press and hold it for at least 5 seconds. This should trigger the fault code to display normally on the monitor.
For John Deere M Series: Use the roller dial and select buttons on the dashboard to navigate to the diagnostic section and view active trouble codes.
What John Deere vehicles throw fault codes the most?
All kinds of John Deere vehicles will throw fault codes. Whatever make or model throws the most fault codes depends more how its maintained than the vehicle itself. That said, John Deere’s E and M series tractors tend to be what people need fault code troubleshooting help with the most (in our experience).
Conclusion
John Deere fault codes are a valuable tool in diagnosing machinery faults. As we have seen in this article, understanding these codes, obtaining them, and decoding them is essential in resolving faults. Regular maintenance and servicing, as well as prompt repairs, are key to avoiding fault codes in the future. Follow these guidelines to keep your John Deere machinery running optimally and efficiently.
