5 Common John Deere 6420 Problems with Simple DIY Fix

John Deere 6420 has stirred quite a fuss in the market. The JD 6420 users have expressed positive reviews about this tractor. Hence, the popularity of the 6420.

But it’s not completely free from issues. So, what are the John Deere 6420 problems?

The common John Deere 6420 problems are related to electrical malfunctions, fuel consumption, engine shutdown, shaking engine, and shifting steering wheels. These problems occur for various reasons, such as faulty sensors, insufficient fuel supply, corroded wiring, etc.

Depending on the type of problem and the reason behind it, there are specific fixes to apply.

Common John Deere 6420 Problems

Quick Overview of John Deere 6420 Problems, Reasons, Solution

John Deere 6420 electrical problemsHaving problematic sensors.Replace the sensor with a fresh one.
Tractor consuming an excessive amount of fuelConstant hydraulic pumping.Take out the battery and install a new one.
The tractor engine shuts abruptlyNot enough fuel supply.Clean the fuel line.
Engine shudders after startingA faulty electrical circuit, injector, or solenoid.Check the starting choke.
Tight Steering WheelHydraulic oil level is not at the appropriate levelFix the hydraulic oil level.

Problem 1: Electrical Problems of John Deere 6420

Some John Deere 6420 owners face electrical issues with the tractor. It starts with the engine rev settling at 1400 rpm whenever the accelerator reaches its full limit.

You might also notice an error code indicating a shorted-out sensor. This might happen due to a fuel line problem. But if the fuel lines are intact, it’s a major electrical problem that you need to fix.

Reason: Corroded Wires and Damaged Sensors

The most common reason behind the electrical issues of the john deere 6420 is damaged wires.

Rodents or other small animals may chew the cables inside the tractor and corrode them entirely. This inhibits electricity conductivity. As a result, the sensors won’t work.

Solution: Replace the Damaged Wires and Sensors

To make the sensors work, you have to fix the wires first. Search the whole tractor for damaged cables and replace them with fresh ones.

But if the problem is in the sensor, you have to replace that sensor immediately. Make sure you solder the new sensor properly. Finally, check the connection using a multimeter.

Problem 2: The Tractor is Consuming Excess Fuel

Another problem arises when the John Deere 6420 consumes excess fuel. Commercial mowers consume 1.1 to 1.9 gallons per hour. If your tractor consumes more fuel than the average, this means you got a problem.

In an era where fuel prices reached the sky, it’s concerning when your tractor needs more fuel than usual.

Reason: Constant Hydraulic Pumping

This often happens when the hydraulic pump constantly pumps oil. It’s possible that something is making the pump discharge entirely. Sometimes voltage issues can also trigger the hydraulic sensor.

John Deere 6420 Constant Hydraulic Pumping
Source: Green Tractor Talk

Solution: Replace the Battery

If you notice such a problem, you must invest in a good battery. By replacing the battery, you can solve this problem instantly.

As a result, the hydraulic sensors will start giving proper signals. So, the hydraulic pump will stop unnecessary pumping and eventually use only the required amount of fuel.

Problem 3: The Tractor Shuts off Abruptly

Sometimes, the JD 6420 doesn’t run as it’s expected. It shuts off after 3-5 seconds of initiation.

Reason: Low Fuel Supply

The main reason this happens is the low fuel supply. The fuel line can get clogged and dirty. This leads to a blockage in the fuel line. So, there’s a shortage of fuel supply to the engine.

Solution: Clean the Fuel Tank and Fuel Lines

To make your JD 6420 run again, you must clean the fuel lines following the steps below:

  • First, you have to remove the fuel cap.
  • Then, take the fuel-catching container and place it under the fuel tank.
  • You’ll see fuel line nuts on the fuel tank. Unscrew these nuts.
  • After that, remove any sediment at the base of the tank. Blow out all the dirt and debris using an air compressor.
  • Then, replace the fuel lines and screw them with diesel fuel line nuts.
  • Drain the water separator and set up new fuel filters.
  • Pour fresh diesel fuel into the tank.
  • Finally, reattach the fuel cap and start the engine.

If the engine is working fine, congratulations! You did a great job.

Problem 4: The Tractor Engine is Shaking After Starting

Many John Deere 6420 tractor owners complain about the engine shaking right after starting it. It’s a common problem, and there are a few reasons why it happens.

Reason: The Electrical Components are Damaged

Engines rely heavily on electrical components such as electrical circuits, solenoids, and fuel injectors.

The engine can’t operate properly if any of these components are corroded or damaged. This leads to the shakiness of the engine after starting.

John Deere 6420 Electrical Components are Damaged
Source: Green Tractor Talk

Solution: Check the Starting Choke

The first thing you have to do is check the starting choke. See if it’s stuck inside the fuel pump. If this is the case, you have to remove the choke.

Also, diagnose the electrical circuit. If you find any damages, repair the faulty circuit or solenoid.

Problem 5: The Steering Wheel is Tight

Again, it might be hard to steer the wheels of the John Deere 6420. It’s possible that the tractor’s inner components have some defects. And there could be multiple reasons behind it.

Reason: Low or High Hydraulic Oil Level

When the hydraulic oil level is extremely low, the steering wheel gets tight. This is the core reason for hard-shifting steering wheels. If there isn’t enough oil, the steering pump won’t be able to function properly.

Again, you’ll face the same difficulty if the hydraulic oil level is higher than the required amount. Then, the oil will flow out of the system and cause steering wheel problems.

Sometimes a worn-out steering pump is also responsible for a tight steering wheel.

Solution: Keep Hydraulic Oil at the Appropriate Level

So, the first thing you should do is check the power steering. See if the hydraulic oil is enough to run the wheel smoothly. If there’s any wear and tear, make sure you repair it immediately.


How Do You Reset the Code on a John Deere?

To reset the code on a John Deere, first, you have to Press MENU on the monitor for 5 seconds. You’ll see the CODES appear on the display. Then, press SELECT to view the machine and engine diagnostic codes. Write the codes down and follow the following process: SELECT>END>SELCT>WAIT>SELECT. The codes will get reset.

What Causes a John Deere Not to Start?

John Deere doesn’t start if there’s any fault in the wiring system. Either the wires are corroded or not plugged in properly. A bad battery is also responsible for not starting the John Deere tractor. So, in this case, you must check the battery’s health and connections to see if they’re all intact.

What Does the Blue I Light Mean on a John Deere Tractor?

The blue I light is an alternator indicator light on a John Deere tractor. It indicates whether there’s a problem with the alternator or not. If you notice the light is ON, this means the battery is unable to stay charged.

Final Words

I hope you’re aware of the John Deere 6420 problems. As you’ve read the whole article, you can now fix any of the tractor problems.

But I’ll suggest you check the wiring and overall health of the tractor every six months. Frequent maintenance can help you get rid of the problems daily.

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