By Ezra Lane If you're encountering the P0138 Nissan code, it implies a high voltage issue at the O2 sensor in bank 1, sensor 2 of your vehicle. This often results from a rich fuel mixture or a direct sensor malfunction. It could also indicate problems such as faulty wiring or an exhaust leak. You'll likely notice symptoms like the check engine light turning on, decreased fuel efficiency, rough idling, and a strong exhaust smell. Addressing these signs quickly prevents further damage, especially to your catalytic converter. Repair involves diagnosing with an OBD-II scanner, checking the wiring, or replacing the sensor. Addressing this issue soon can enhance your understanding of vehicle maintenance and potentially prevent more severe problems.
P0138 Nissan Code Meaning
The P0138 code in a Nissan indicates the O2 sensor in bank 1, sensor 2, is detecting high voltage, suggesting low oxygen in the exhaust.
Potential causes include a rich fuel mixture, sensor malfunction, faulty wiring, exhaust leaks, or fuel injection issues.
Investigate and resolve these to fix it.
Error Code P0138 Symptoms
If your Nissan shows the P0138 error code, you might notice a few signs that something is wrong with the oxygen sensor. Catching these early can help avoid bigger problems.
Look out for these signs:
- Check Engine Light: This light will come on your dashboard. It's a signal from your car that something needs attention.
- Poor Fuel Economy: Your car might use more fuel than usual. The sensor can't give correct oxygen level data, so the engine uses more fuel than it needs.
- Rough Idling: The car may idle roughly or even stop. This happens because wrong sensor readings mess up the fuel and air mix, affecting how the engine runs.
- Unusual Exhaust Smell: You might smell sulfur or rotten eggs from the exhaust. This means combustion isn't complete, and it's time to check the sensor.
These signs can tell you if the O2 sensor has problems.
Causes of Nissan P0138 Fault Code
If you see the P0138 code on your Nissan, it means there's an issue with the oxygen sensor circuit on Bank 1, Sensor 2.
Here's why it might happen:
- Bad O2 Sensor: Oxygen sensors can go bad because of dirt, heat, or broken wires, giving wrong voltage signals.
- Exhaust Leaks: A leak near the sensor lets extra air in, messing up the sensor's readings and causing high voltage.
- Wiring Issues: Wires can get shorted, especially if they touch power sources. Check for worn or damaged wires.
- Broken Engine Control Module (ECM): Sometimes, the ECM can misread the sensor's signals, causing this code.
Fix these to make sure your car runs well and uses fuel efficiently.
Tools Needed to Diagnose
To figure out a P0138 error code on your Nissan, you need some specific tools. This involves checking the oxygen sensor and its wiring.
Here's a simple list of what you'll need:
- OBD-II Scanner: Use this to read error codes and data from your car's computer.
- Digital Multimeter (DMM): This checks the voltage and resistance in the O2 sensor to see if it's faulty or if there's a wiring issue.
- Back-probe Pins: These connect to the sensor's terminals without damaging the wires.
- Nissan Repair Manual: This has important information and diagrams for your car model to help you fix the problem.
Make sure your tools work well and follow safety rules when working with car electronics.
How to Fix P0138 Nissan Error Code – Step by Step
Step 1:
Ensure that your engine is cool before starting. Locate the O2 sensor responsible for the P0138 error on your Nissan. This sensor is the post-catalytic converter sensor on bank 1. Disconnect the sensor's plug to proceed.
Step 2:
Using an O2 sensor socket, carefully remove the faulty sensor by turning it counterclockwise. Once it's loose, gently pull it out from its position.
Step 3:
Before installing the new sensor, compare it with the old one to ensure it's the correct replacement.
Apply an anti-seize compound to the threads of the new sensor to facilitate future removals, but be cautious not to get any compound on the sensor's tip, as this could impair its function.
Step 4:
Carefully screw in the new sensor by hand to avoid cross-threading. Once it's in place, use the socket to tighten it securely.
Step 5:
Reconnect the sensor's plug, ensuring it snaps into place securely. Double-check all connections and fittings before starting your engine to ensure the error code is resolved.
Common Diagnosis Mistakes
When dealing with the P0138 error code on a Nissan, it's easy to make a few common mistakes. Here's how to avoid them:
- Check the Wiring and Connectors: Sometimes the problem isn't the sensor itself. Look for wear, corrosion, or damage in the wiring or connectors before replacing the sensor.
- Understand Sensor Data Properly: If the O2 sensor shows high voltage, it mightn't be broken. It could be due to a bad fuel injector or wrong fuel pressure.
- Look for Exhaust Leaks: An exhaust leak before the sensor can give false readings. Inspect the exhaust system to ensure there are no leaks affecting the sensor data.
- Replace the Correct Sensor: The P0138 code is about Bank 1 Sensor 2. Don't mistakenly change Sensor 1 or a sensor on the wrong bank, as this won't fix the issue.
P0138 Nissan Repair Cost
The cost to fix a P0138 error code in a Nissan can vary, but it's usually not too high. This code means there's a problem with the oxygen sensor in bank 1, sensor 2. The main costs are the sensor and the labor to install it.
- Oxygen Sensor Cost:
- The price for a new O2 sensor is between $20 and $250.
- The brand and quality affect the cost.
- Some Nissan models need specific sensors, which might be pricier.
- You can choose aftermarket parts to save money, but make sure they fit your car.
- Labor Cost:
- Labor can range from $50 to $150.
- It depends on the mechanic's rate and where you are.
- Some places offer lower prices, but it's smart to hire someone who knows Nissans well.
Related Error Codes on Nissan
Your Nissan might show some error codes related to the P0138 code. Recognizing these codes can help you find and fix issues before they get worse. Here are some codes to know about:
| Code | Description | Common Cause |
|---|---|---|
| P0137 | Low voltage in O2 sensor circuit (Bank 1, Sensor 2) | O2 sensor might be faulty or wiring has a short to ground |
| P0139 | Slow response in O2 sensor circuit (Bank 1, Sensor 2) | Catalytic converter could be clogged or O2 sensor might be faulty |
| P0140 | No activity in O2 sensor circuit (Bank 1, Sensor 2) | Could be wiring issues or bad connection to O2 sensor |
| P0171 | System is too lean (Bank 1) | Might be vacuum leaks or not enough fuel pressure |
| P0174 | System is too rich (Bank 1) | Could be leaking injectors or fuel pressure is too high |
These codes relate to problems with the oxygen sensor or fuel system, like the P0138 code. Fixing one problem might help with others, or give you more clues on what's wrong. Check connections and wiring first, as these are often the issue. If problems continue, you might need a professional mechanic to look into it further.
Can I drive safely with P0138 Nissan?
Yes, you can drive your Nissan with the P0138 code, but it's not good to wait too long.
The code means there's a problem with an oxygen sensor. It can make your car use more gas and might damage the catalytic converter if not fixed soon.
People Also Ask
What Is the Function of Bank 1 Sensor 2 in Nissan?
Bank 1 Sensor 2 in a Nissan car checks the exhaust gases after they pass through the catalytic converter. It makes sure the converter is working well to reduce pollution. If this sensor doesn't work right, it can affect how well your car runs.
How Does Weather Affect the P0138 Error Code?
Weather can make the P0138 error worse. In cold weather, car fluids get thicker, which might affect the O2 sensor. In hot weather, the sensor can become more sensitive, causing it to give higher voltage readings.
Is P0138 Nissan Code Common in Specific Nissan Models?
Yes, the P0138 code is more common in some Nissan cars, especially older ones or those not well taken care of. This code is about a problem with the car's sensors and emission system, which can happen if the car isn't maintained regularly.
Can DIY Repairs Permanently Fix the P0138 Code?
Yes, you can fix the P0138 code by yourself if you know how to fix cars. Usually, changing the bad O2 sensor and checking that nothing else is wrong can solve the problem. Make sure you follow steps carefully for a good fix.
Does the P0138 Code Affect Fuel Economy?
Yes, the P0138 code can make your car use more gas. This happens because the engine might use too much fuel, making it run "rich." As a result, you might see lower miles per gallon, meaning you'll need to fill up the tank more often.