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Modern vehicles have become very complex machines, which is why they now have computer systems that monitor their performance.

On-board diagnostics (OBD) is a system that collects information about a vehicle’s health through a network of sensors. The information gathered from these sensors is used to regulate different vehicle systems. It’s also used to alert the user or driver of any issues and problems with the car or its components.

When a sensor sends data to the vehicle’s main computer that’s not within the expected range, the computer stores this information as a diagnostic trouble code (DTC). This code is a combination of letters and numbers that indicates the nature and source of the issue. DTCs are typically standardized but may also be manufacturer-specific.

What Does the P0059 Code Mean?

Diagnostic trouble code (DTC) P0059 stands for “HO2S Heater Resistance (Bank 2, Sensor 1).” This code may be set when the vehicle’s powertrain control module (PCM) detects that there is an issue with the heater circuit of the oxygen (O2) sensor. It may also set if the PCM detects a level of resistance from the upstream or pre-catalytic oxygen sensor heater circuit that’s greater than the specified range. The malfunction indicator lamp (MIL) may illuminate when this code is set.

The “Bank 2” in this code’s definition refers to the side of the engine that does not contain cylinder number one. The “Sensor 1” in the definition refers to the sensor closest to the engine assembly.

Note: The definition of code P0059 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

Oxygen sensors are typically mounted in the exhaust manifold or downstream from the manifold, in the exhaust pipe. The vehicle’s computer system uses these sensors to measure the oxygen content in the exhaust.

Many oxygen sensors have a sensing element inside a metallic housing. This sensing element is made of Zirconium, an electrically-conductive material that’s capable of producing a small voltage when it comes into contact with oxygen.

heated oxygen sensor 5a
The vehicle’s computer system uses oxygen sensors to measure the oxygen content in the exhaust.

These sensors also have a heating element that helps them reach their operating temperature faster. Oxygen sensors need to be at a certain temperature for them to produce more accurate readings of the oxygen content in the exhaust. The PCM monitors the oxygen sensor’s heater circuit for unusual activity. When the PCM detects a potential problem with this circuit, it sets the P0059 code. The vehicle’s malfunction indicator lamp (MIL) or check engine light may also illuminate to alert the driver or user of the presence of the issue.

Vehicles that are prone to code P0059 include various models of Chevrolet (especially Chevy Silverado), Ford, GMC, Cadillac, and Mercury.

What are the Possible Causes of the P0059 Code?

Like many trouble codes, there are quite a few reasons why the P0059 engine code may set. Below are just some of the possible causes for this code.

  • HO2S failure
  • HO2S heater low control circuit is shorted to ground or shorted to voltage
  • HO2S connector is damaged
  • HO2S heater ignition circuit is open
  • HO2S heater low control circuit is open or has a high resistance condition
  • PCM failure

What are the Common Symptoms of the P0059 Code?

The P0059 code has a handful of signs that may alert the vehicle’s user or driver of an existing issue. If you experience any of the following codes, it’s best to address the issue immediately to prevent further complications.

  • Malfunction indicator lamp (MIL) or check engine light illumination
  • Decreased engine performance
  • Increased fuel consumption
  • A rich running condition
  • Other related DTCs may be stored
check engine light ona
THe malfunction indicator lamp (MIL) or the check engine light may illuminate if the P0059 code is stored.

How to Diagnose the P0059 Code

Diagnosing and troubleshooting OBD-II codes such as P0059 can be challenging to many. In order to reach a long-term solution, the root cause must first be determined. However, with the number of possible causes, the troubleshooting process may take up a bit of time and effort.

Trouble code diagnosis may be difficult, but it’s not impossible. Repair manuals and databases offer accurate and specific information about the P0059 engine code repair process. Moreover, they also contain detailed diagrams and illustrations that are easy to follow. For the visual learner, however, other resources are also available.

How to Fix the P0059 Code

As mentioned above, troubleshooting codes such as the P0059 engine code is difficult. This is because no two vehicles are built and oriented the same. The solution for the P0059 code on Chevy Silverados may be different from the solution to P0059 on GMC Sierras. Also, there are a handful of possible causes per trouble code. Troubleshooting will take a lot of time and effort.

For the experienced DIYer, repair manuals and databases may provide them with the information they need to address the issue on their own. However, if you’re not as experienced or confident in your repair skills, it’s better to have a certified mechanic or technician do the repairs for you. This is to avoid mistakes that may lead to even more problems and even more expensive fixes.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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