Harley Code P0051 - What's Wrong and How to Fix That?

Harley Davidson motorcycles are more than just performance and quality. They are also a reflection of the lifestyle of a person. This is the reason why the famous American brand has retained its identity and relevance for over a century, and its motorcycles are regarded as one of the dream bikes of riders.

P0051 code highlights

• Level of urgency:Medium
• Possible culprits:oxygen sensor overheated or dead
• Price for repair:$500 - $1,200
• If neglected:Emission problems, fuel consumption issues, harsh work of the engine
• DIY repairs:Possible but complicated
• Can you drive?Yes

What the Fault Code P0051 Means for Harley Bikes

The P0051 fault code on Harley Davidson bikes is an indicator of an O2 sensor circuit that is getting insufficient current. It typically occurs when the oxygen sensor signal voltage is lower than normal, or when there is a lack of fuel being supplied to the exhaust system.

This could be due to a variety of issues such as a faulty fuel injector, clogged air filter, malfunctioning oxygen or air-fuel ratio sensor, vacuum leak, or weak fuel pump.

If left unchecked for long enough, the problem can lead to further damage in other parts of the engine. Reduced performance and poor fuel economy are also common symptoms associated with this particular fault code. The best way to remedy this problem is by first identifying the underlying cause, and then taking the necessary steps to fix it.

Depending on what is causing the issue, the solution may involve replacing faulty parts or simply performing a thorough cleaning and inspection of the engine components. Whatever the case may be, it is important to ensure that all necessary repairs are conducted immediately to prevent any further damage from occurring.

Most Common Causes of the P0051 Fault Code in Harley Bikes

The most common problems associated with the P0051 code in Harley bikes are electrical in nature. With that, here are the usual culprits triggering the issue:

1. Heater Circuit Wiring or Connector Issues

The P0051 fault code in Harley bikes is usually triggered by heater circuit wiring or connector issues. A visual check-up of the wiring and connectors is recommended to start assessing the problem.

One should be looking for any corroded, frayed, burnt, or disconnected wires as a sign of faulty connections. Testing with diagnostic tools such as an OBD scan tool can also help in confirming the presence of an issue.

The process of checking and diagnosing the problem should be done systematically before ruling out that the sensor itself is faulty. First, inspect all wires for any signs of damage. If none is found, check for loose connections or corrosion buildup at the connectors. Then, using an OBD scan tool can help to confirm any fault codes present coupled with the use of a multimeter to check for broken connections.

The possible solutions depend upon the extent of damage caused due to faulty connections. If there are minor damages, simply cleaning off corrosion and tightening up connections might do the trick.

However, if more serious damage has been detected and the multimeter reading signifies a very high resistance or no connection at all in the wirings or connectors, one should not hesitate to replace damaged lines, pins, or connectors completely, along with rewiring part of the circuit when necessary.

It is worth noting that incorrectly inspecting and repairing the wiring of the heater circuit can result in further damages, or even more fault codes. For this reason, it is always recommended to consult a professional mechanic if you are not confident enough in your skills.

A simple mistake may lead to unnecessary time and money spent on repairs, so make sure to double-check everything before starting the repair process.

2. Blown Fuse

A blown fuse in a Harley bike can result in the P0051 fault code, which is an indicator that there has been a malfunction of the oxygen sensor. This code typically appears when the fuse has failed to provide the necessary power needed for the oxygen sensor and control module to function properly.

When assessing whether a fuse is blown, look for any visual signs or corrosion on it first. If you notice any discoloration, burn marks, melted plastic parts, warped metal components, or corrosion, then you should replace it immediately with one that has identical specifications.

You can also use a multimeter to test its continuity by connecting each end of the fuse to its contact points and measuring the resistance between them. If there is no flow of electricity, then it's another guarantee that your Harley's fuse needs a replacement.

The most common cause of a blown fuse is an overload of current. This occurs when there is too much electrical power is being drawn from the battery, creating a dangerous level that can lead to component damage or even a fire in extreme cases. Other potential causes include faulty components, improperly installed wires, and corrosion due to moisture or water seeping into the wiring harness.

To prevent your Harley bike's fuse from blowing again, you should check all related components (such as the oxygen sensor) for any problems before replacing it. You should also replace any damaged wiring and ensure that everything has been securely fastened together.

For a good measure, see to it that your Harley bike's fuses and other electricals are protected from moisture and sources of extreme temperatures that could cause them to overheat. All these will help reduce the chance of your fuse being blown again in the future.

3. Defective Oxygen Sensor

If the trouble persists after you have checked the wirings, connections, and fuses, then it's time to address the elephant in the room, which is a possible defect or damage to the oxygen sensor. In Harley bikes, a defective oxygen sensor can result in a P0051 fault code.

The common cause behind this problem is the oxygen sensor's internal failure due to age or damage from engine heat and vibration, poor electrical connection, short circuit malfunctioning of the control circuit of the sensors, or even faulty wiring harnesses leading to incorrect information being sent.

To assess signs of a bad oxygen sensor, you can use visual inspection such as checking for cracks on the wires and connectors. You can also use specialized tools like a multimeter or an oscilloscope to measure voltage drop or resistance.

When it comes to maintenance, if your oxygen sensor is only dirty then you can clean it by taking off the air filter box assembly and getting access to the oxygen sensors.

Make sure you take necessary safety measures when performing maintenance and always make sure that the air filter is clean and properly installed before any test runs. If cleaning the sensor doesn't help, then replacement is required.

When purchasing a replacement oxygen sensor, make sure you get one matching your bike's specifications as every vehicle has different requirements for size, temperature range, and other factors.

4. ECU Malfunction

It is important to remember that even if one finds and fixes the source of the problem, a simple resetting of the engine control unit (ECU) may still be necessary for the P0051 fault code to disappear completely from Harley bikes. So, make sure to do this before concluding that you have fixed the issue. However, if the problem persists, then you may be dealing with a possible ECU software malfunction.

Software corruption can occur when incorrect programming files are written or when the ECU memory becomes damaged due to a problem with its internal power supply. In addition, if there is too much electrical interference from other devices on the network or from electrostatic charges within the vehicle itself, this can also cause corruption in the ECU's software.

If you experience this with your Harley bike, it is best to first check the ECU software to ensure that it is running correctly and has not become corrupted. If this is found to be the case, then you should attempt to reprogram the ECU using a computer or a device with a special app that can be plugged into your bike. This will allow you to reflash the ECU software to restore its proper functionality.

It is important to note, however, that if the issue persists after being reset, then it may be necessary to replace the entire ECU hardware with a new one in order for the fault code to go away completely. In any case, it is always best to consult an expert mechanic or technician to properly diagnose and resolve this issue.

Conclusion

The P0051 fault code of Harley points out to low voltage supply in the operation of the oxygen sensor. However, before pointing the blame at the sensor itself, it's important to check the wiring, sensor, and fuse affecting that part first. Once you have ruled them out as the possible culprits, proceed to check the sensor itself for possible defects while also assessing the ECU for any possible issues.

Taking into account all these considerations should help you diagnose and fix the P0051 code stemming from oxygen sensor issues in Harley bikes with ease.