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Diagnostic trouble codes, also known as "fault" or "engine" codes, are unique five-digit identifiers indicating a specific problem has been detected by a vehicle's computer. These codes can aid with problem diagnoses and give car owners a heads-up on issues so they can resolve them before they worsen.
In this article, we'll be reviewing the P0135 code, which indicates an O2 sensor heater circuit malfunction in bank 1, sensor 1. We'll start by covering exactly what this means, as many car owners find it a bit confusing.
Then, we'll cover some symptoms you may come across while a P0135 is active, its potential causes, and its overall severity. Finally, we'll explore diagnosing and inspecting for a P0135 code, ensuring you're fully prepared to address it.
What is the P0135 Code and the Symptoms?
Oxygen sensors (O2 sensors for short) monitor how much oxygen is in a vehicle's exhaust gasses, which the engine uses to adjust its air-fuel. One key part of this process is a built-in heater element that quickly brings the sensors up to their operating temperature.
Oxygen sensors (O2 sensors for short) play a crucial role in engine management. They monitor the amount of oxygen in a vehicle's exhaust gasses, providing feedback to the engine's computer.
This feedback allows the engine to adjust its air-fuel mixture for optimal combustion. An O2 sensor works by producing a voltage based on the difference in oxygen levels between the exhaust gas and the outside air.
One advancement in O2 sensor technology includes a built-in heater element.
A heated O2 sensor has this internal heater circuit, which ensures the sensor reaches its operating temperature more swiftly than an unheated one. This rapid warm-up is key to the engine running smoothly, especially during its initial start, ensuring the proper air/fuel mix and faster engine warm-up.
If a vehicle is displaying a P0135 code, it means something is amiss in the first O2 sensor's heater circuit, such as a short in the circuit or excessive resistance.
O2 sensors are key in maintaining optimal combustion, so if your car currently has a live P0135 code, you'll likely experience a few symptoms; below are the most common.
- Check Engine Light: The first and most likely symptom of a P0135 code is a check engine light appearing on your dashboard. This light can be triggered by various issues, but a diagnostic scan can confirm if the P0135 code is the cause.
- Engine is Slow to Heat Up: The heater in an O2 sensor ensures that the sensor reaches its operating temperature efficiently. A faulty heater circuit in the O2 sensor can cause the sensor to take longer than usual to warm up, which can indirectly affect the engine's performance, especially in colder climates.
- High Fuel Consumption: O2 sensors help regulate fuel consumption by monitoring the oxygen content in the exhaust gasses and sending this data to the vehicle's computer. When they're not working correctly, the system may add more fuel than necessary, resulting in more frequent trips to the gas station.
- Rough or Inconsistent Idle: Another symptom of a P0135 code is a rough or inconsistent idle. If your engine isn't running as smoothly as usual, with RPMs fluctuating inconsistently, it may be a bad O2 sensor heater preventing regulation of the air-fuel mixture.
- Black or Foul Smelling Exhaust: Finally, if your car emits black or foul-smelling exhaust fumes, a faulty O2 sensor may be to blame. This is because a bad sensor can throw off the engine's air-fuel mix, causing incomplete combustion and releasing unburnt fuel into the exhaust.
How Serious is the P0135 Code and What are the Causes?
Overall, a P0135 code carries a Medium level of severity. While it might not cause immediate damage or leave you stranded, addressing it sooner rather than later is important for maintaining optimal engine performance and preventing long-term harm.
Ignoring a P0135 code for too long can diminish your engine's performance and efficiency and, in severe cases, indirectly damage the catalytic converter.
Here are some of the most common causes behind a P0135 code:
- Bad O2 Sensor Heater Element: The main cause of a P0135 code is a bad O2 sensor heater element. These can wear out or malfunction over time, preventing the sensor from reaching its operating temperature in a timely manner.
- Damaged or Loose Wiring: If an O2 sensor's wiring becomes damaged, corroded, or loose, it can disrupt the flow of electricity to the heater element, leading to inefficient or non-existent heating.
- Faulty Coolant Temperature Sensor: The engine's computer relies on the coolant temperature sensor to gauge the engine's temperature. If this sensor isn't working as it should, it can send incorrect data, affecting the heater's operation.
- Malfunctioning ECM: The Engine Control Module (ECM) controls the operation of the O2 sensor's heater element. However, if the ECM itself is bad, it might not regulate the heater correctly, triggering the P0135 code.
- Blown Fuse: A simple but often overlooked cause is a blown fuse. If the fuse connected to the O2 sensor's heater circuit blows, it will cut power to the heater, keeping it from working as intended.
Can I Still Drive with a P0135 Code on My Car?
Yes, in most cases, you can still drive your vehicle if it's showing a P0135 code.
Just note that this code indicates a fault in the O2 sensor's heater circuit, which might not cause immediate breakdowns or severe engine damage but can lead to poor fuel efficiency, engine performance, or any of the other symptoms mentioned earlier.
Over time, these issues can strain other parts of your vehicle, such as the catalytic converter. Moreover, a P0135 causing higher emissions means driving isn’t just further taxing your engine, but also the environment.
For the best experience, it's always best to address diagnostic trouble codes soon after they appear to prevent premature engine wear.
How Can I Diagnose a P0135 Code?
When diagnosing a P0135 code, the best place to start is with a reliable OBD-II scanner. These handheld devices plug directly into a vehicle's OBD-II port and can quickly scan your system for codes.
Once you've confirmed the presence of the code, visually inspect the O2 sensor in bank 1, sensor 1, and its wiring. Look for signs of damage, wear, or disconnection.
Next, using a multimeter, check the resistance of the heater circuit in the O2 sensor. If resistance is outside the manufacturer's specifications (usually between 10Ω and 20Ω), the sensor might be faulty. Finally, inspect the O2 sensor's heater circuit fuse to ensure it's intact.
If you're unfamiliar with these procedures or if the issue isn't evident after these checks, your best bet is to consult a mechanic. They'll have the tools and expertise to pinpoint the exact cause and suggest a solution.
How Difficult is it to Inspect a P0135 Code?
Inspecting a P0135 code can range from straightforward to moderately challenging, depending on how savvy you are with automotive diagnostics and the specific issue causing the code.
For those who are mechanically inclined, the initial steps—like using an OBD-II scanner to confirm the code and visually inspecting the O2 sensor and its wiring—are relatively simple.
Yet, more in-depth diagnostics, such as testing the heater circuit's resistance with a digital multimeter or checking related fuses, might require a bit more expertise and confidence.
For owners without any hands-on experience with car repairs, even the basic steps can seem daunting.
The important thing is that the root cause of the issue is resolved, so if you're unsure at any stage, it may be best to simply turn things over to a trusted mechanic.
JEGS: For All Your Automotive Needs
There you have it, the full rundown on the P0135 diagnostic trouble code. While a faulty O2 sensor heater may not necessitate pulling over immediately, you will want to diagnose and repair it before it becomes a bigger headache.
For all your automotive needs, consider JEGS, a leading supplier of performance auto parts. Still have questions? Contact our team today.
