HARLEY CODE P0051 – WHAT’S WRONG WITH THE TERM AND HOW TO FIX THAT?

Most Harley Davidson owners frequently encounter the trouble code p0051. If you own this vehicle, you should know this code well. If this issue is not fixed at the primary level, it may cause more critical issues in your bike.

So,  what is Harley Code P0051? This code indicates less voltage in the heater circuit. And because of this, the O2 sensor won’t get enough heat to measure the exhaust gas’s oxygen level correctly. Fixing the faulty ECU O2 sensor and heater circuit can resolve this issue.

In this article, we will discuss the symptoms and causes of this trouble code. You will also learn about the individual fixes and precautions while fixing them. Keep reading till the end to learn more about the code.

Symptoms of Harley Code P0051 You Will Experience

The symptoms of this case are not usually noticeable because they don’t obstruct the vehicle from running. You might have to use a digital diagnosis device to be sure about this code fault.

But sometimes, the vehicle may show a few symptoms by which you can detect the code fault. Those are:

•  The check engine light may keep flashing frequently
• Generally when the air-to-fuel ratio gets imbalanced, the engine starts to run roughly. This could be the symptoms of any of Harley code p0031 or  p0051
• The poor fuel economy sometimes indicates code P0051
• Difficulty in starting the engine

Most Common Causes of Harley Code P0051 and Fixes

You can think of the P0051 as a Heater Control Circuit Low (Bank 2 Sensor 1). Though it’s one of the prime reasons behind this code, it’s not the sole reason and fact here. The P0051 code can originate for many reasons, and the low voltage in the heater circuit is one of them.

Usually, each of those reasons requires different fixes. Here are a few common causes of the p0051 fault code, along with their solutions:

No	Causes	Solutions
1	Fault in Oxygen Sensor	Check for any cracks or damages present there
		Clean the sensor
2	Fault in ECU	Ensure the smooth running of the software
		Replace the hardware if needed
3	The issue with the heater circuit wiring	Clean corrosion or replace lines or pipes
4	Blown off the heater circuit fuse	Have to exchange with a new one
5	Excessive and low pressure of fuel	Check the gas tank and fuel lines

Now, we will discuss each of the reasons and their fixes explicitly:

1)   Fault In Oxygen Sensor

A faulty Oxygen sensor is a primary reason for this DTC(Diagnostic Trouble Code). The vehicle will show the code immediately after any damage occurs in the oxygen sensor.

Other reasons for internal damage are

• Faulty electrical connection
• Heavy vibration
• Short circuit
• If due to Harley code p0132, the oxygen sensor remains at a high voltage for a prolonged period

However, age is another factor that can result in this problem. The oxygen sensor corrodes and may show some defects if it gets old. Besides, dirt present in the sensor can also cause this.

Fixes

• Step 1: You have to detect any defect on the sensor. Check for any wear or cracks present in the connections or not
• Step 2: Measure the resistance of the sensor to determine the defects
• Step 3: Clean the sensor manually to remove dirt or debris
• Step 4: If these fixes don’t work, then the last option you have is to replace the oxygen sensor with a new one

2)   Fault In ECU

The Engine Control Unit (ECU) is an essential issue in showing the code P0051. Because after fixing all other problems, the problems in ECU can still result in this fault code. Mainly, the fault in the ECU software causes this issue.

False programming is the reason behind corrupted software. However, ECU gets the power supply internally, and this power may also cause malfunctioning in ECU. Sometimes, an electrical crisis can also cause the failure of the ECU.

Fixes

• As it depends on the software, the primary fixing is to ensure the safe running of the software
• Check and find if the software is corrupted or not, then fix it
• A new program may also fix this problem
• If these don’t work, you have to replace the ECU hardware

3)   Issue With Heater Circuit Wiring

This is one of the main culprits in showing Harley Code P0051. Most of the time, the disconnection of wires leads to the issue. However, fraying or burning of wires due to overvoltage also results in this fault code.

Another concern is the corrosion of wires. Moreover, external or internal damage to the wires will also lead to this crisis.

Fixes

• First, determine if any damages are present on any wires. Either fix or replace those defective wires
• Inspect and find if any connection is loosened. Then, tighten them correctly to secure the proper connection
• Also, check for corrosion
• After fixing all the parts, then double or triple inspection to ensure the proper fixing

4)   Blown Off The Heater Circuit Fuse

The primary function of the fuse is to provide adequate power for the proper working of the oxygen sensor. It also functions to control the module. Hence, if the fuse fails to fulfill its primary function, Code P0051 appears. In most Harley-Davidson vehicles, it is a typical case.

Likewise, the primary reason behind not providing power is blowing off that fuse. If there is an overload of current, it will lead to the proper blowing of the fuse. Besides, the unusual connection of wires can also cause this issue. 

Fixes

• Check the current flow. Fix if there is an unnecessary and unusual flow of current
• If there is no flow of current, it should be an issue of concern. In most cases, you might have to replace the fuse
• Ensure the safety of the fuse from high temperatures
• Check and Replace the damaged wiring also

5)   Excessive and Low Pressure Of Fuel

Generally, the quantity of fuel depends on the oxygen level and can be manipulated by the oxygen sensor. And, if any variation in the pressure occurs, it will cause the code P0051.

However, the quantity of fuel may vary due to many reasons, like a leak in the gas tanks or fuel line.

Fixes

• First, check the fuel lines to see if there are any defects or not. Then, you need to repair or replace those defective fuel lines
• Check the gas tank properly; if you find any damages, leaks, and cracks, repair it
•  Repair or replace the battery if needed

Cautions While Fixing The Harley Code P0051

Every reason has its respective fixes, and if you make mistakes, it might damage your vehicle more. To avoid further issues, here are some cautions that you should maintain.

• While fixing the oxygen sensor, cleaning should be done carefully
• The type of sensor differs from the specifications of each vehicle. That’s why, at the time of replacement of the sensor, make sure you are picking the right one according to your bike’s specifications
• Whenever checking any data, always use a professional-grade scan device
• Follow the user manual if you don’t have experience in handling the vehicle’s parts
• When you are cleaning the wires with chemicals, make sure there is adequate ventilation. Also, don’t forget to wear protective clothes and sunglasses
• Never try to check or handle any wires when the engine is on. This might result in a severe unexpected accident. Thus, during the time checking and connecting wires, make sure you turn off the bike engine
• While replacing the sensor, keep the dirt and grease away from the part. Otherwise, these external impurities will again contaminate the sensor
• Be sure that the circuit is detached during the replacement of the fuse

FAQs

In this FAQs section, we will answer several mostly asked questions about the Harley code p0051.

Final Verdict

Initially, the P0051 code doesn’t pose any severe risks. But if you keep driving the vehicle with this code on, it may damage your engine eventually. Throughout the article, we discussed Harley Code P0051 and its fixes.

There are multiple reasons for generating this trouble code, each requiring different fixing methods. You need to be cautious while fixing to prevent any injury or damage. If you can’t fix the code issue, ask for the professional help from any automotive mechanic.