Introduction
The P0167 diagnostic trouble code (DTC) indicates a problem with the heater circuit in the Bank 2 Sensor 3 oxygen sensor of your vehicle. Oxygen sensors are critical components in your car's emission control system, responsible for monitoring the oxygen content in the exhaust gas. This information is relayed to the engine control unit (ECU), which uses it to adjust the air-fuel mixture for optimal combustion and reduced emissions. The heater circuit within the oxygen sensor ensures it reaches operating temperature quickly, especially during cold starts, allowing it to function accurately and efficiently. A fault in this circuit can lead to increased emissions, reduced fuel economy, and potential engine performance issues.
Comprehensive P0167 Information Table
| Category | Description | Possible Causes |
|---|---|---|
| Code Definition | Heated Oxygen Sensor (HO2S) Heater Circuit Bank 2 Sensor 3. This indicates a malfunction specifically within the heater circuit of the oxygen sensor located after the catalytic converter on Bank 2. | Faulty Bank 2 Sensor 3 Oxygen Sensor Open or shorted wiring in the heater circuit Poor electrical connection in the heater circuit Blown fuse (if applicable) Faulty Engine Control Unit (ECU) (rare) Damaged or corroded connector |
| Sensor Location | Bank 2 Sensor 3 refers to the oxygen sensor located after the catalytic converter on the side of the engine opposite cylinder number one. "Bank 2" identifies the engine bank, and "Sensor 3" is the sensor position relative to the catalytic converter. | Knowing the engine layout is essential for locating the correct sensor. Refer to your vehicle's service manual or online resources for a diagram of your engine and exhaust system. Cylinder number one is typically at the front of the engine. |
| Heater Circuit Function | The heater circuit is designed to rapidly heat the oxygen sensor to its optimal operating temperature (around 600°F or 315°C). This is crucial for accurate oxygen sensing, especially during cold starts when the exhaust gas temperature is low. Without the heater, the sensor would take much longer to warm up, leading to inaccurate readings and increased emissions. | The ECU monitors the heater circuit's resistance and current flow. If the resistance is too high (open circuit) or too low (short circuit), or if the current flow is outside the acceptable range, the P0167 code will be triggered. |
| Symptoms | Check Engine Light illumination Reduced fuel economy Increased emissions Possible rough idling Failed emissions test No noticeable drivability issues (in some cases) |
The severity of the symptoms can vary depending on the vehicle and the extent of the heater circuit malfunction. In some cases, the only noticeable symptom may be the Check Engine Light. |
| Diagnostic Tools | OBD-II scanner Multimeter * Wiring diagram |
An OBD-II scanner is essential for reading the DTC. A multimeter is needed to test the heater circuit's resistance, voltage, and continuity. A wiring diagram is crucial for tracing the circuit and identifying potential problem areas. |
| Troubleshooting Steps | 1. Verify the code with an OBD-II scanner. 2. Inspect the wiring and connectors to the Bank 2 Sensor 3 oxygen sensor for damage or corrosion. 3. Test the heater circuit resistance using a multimeter. 4. Check the fuse (if applicable) for the heater circuit. 5. Inspect the oxygen sensor for physical damage. 6. Test the heater circuit voltage. |
Start with the simplest and most common causes first, such as checking the wiring and connectors. If the wiring and connectors are good, then proceed to testing the heater circuit resistance and voltage. |
| Common Mistakes | Replacing the oxygen sensor without properly diagnosing the problem. Overlooking wiring and connector issues. Failing to check the fuse (if applicable). Assuming the ECU is faulty without ruling out other possibilities. |
Thorough diagnosis is crucial to avoid unnecessary repairs. Always start with the simplest and most common causes first. |
| Related Codes | P0137, P0138, P0140, P0141, P0142, P0143, P0144, P0145, P0146, P0147, P0148, P0149, P0157, P0158, P0160, P0161, P0166, P0168, P0169. These codes relate to other oxygen sensor malfunctions or heater circuit problems in different banks or sensor positions. | These related codes can provide clues about the nature of the problem. For example, if multiple oxygen sensor codes are present, it may indicate a more widespread issue, such as a problem with the ECU or the exhaust system. |
| Sensor Types | Zirconia and Titania. Most modern vehicles use zirconia oxygen sensors. | The type of oxygen sensor can affect the diagnostic procedure. Refer to your vehicle's service manual for information about the specific type of oxygen sensor used in your vehicle. |
| Heater Circuit Resistance Test | Typically, the heater circuit resistance should be between 5 and 20 ohms. Refer to your vehicle's service manual for the specific resistance range for your vehicle. | An open circuit will result in infinite resistance. A short circuit will result in very low resistance. |
| Heater Circuit Voltage Test | The heater circuit should receive battery voltage (approximately 12 volts) when the engine is running. | No voltage indicates a problem with the power supply to the heater circuit, such as a blown fuse or a broken wire. |
| Potential Repair Costs | Oxygen sensor replacement: $100 - $300 (including parts and labor) Wiring repair: $50 - $200 (depending on the complexity of the repair) Fuse replacement: $5 - $20 ECU replacement: $500 - $1500 (rare) |
These are estimated costs and can vary depending on the vehicle, the location, and the repair shop. |
| Impact on Emissions | A faulty oxygen sensor heater circuit can significantly increase emissions, leading to a failed emissions test. | The ECU relies on accurate oxygen sensor readings to properly control the air-fuel mixture. Without the heater circuit, the sensor may not reach operating temperature quickly enough, resulting in inaccurate readings and increased emissions. |
Detailed Explanations
Code Definition: The P0167 code specifically identifies a problem with the heater circuit of the oxygen sensor located after the catalytic converter on Bank 2 (the side of the engine opposite cylinder number one). The heater circuit is essential for quickly bringing the sensor to its operating temperature.
Sensor Location: Bank 2 Sensor 3 is positioned downstream of the catalytic converter on the engine bank opposite cylinder number one. Identifying the correct bank and sensor location is crucial for accurate diagnosis and repair. Refer to your vehicle's service manual for a diagram.
Heater Circuit Function: The heater circuit's primary function is to rapidly heat the oxygen sensor to its optimal operating temperature. This is especially important during cold starts, ensuring accurate oxygen sensing and proper engine management, ultimately reducing emissions.
Symptoms: Common symptoms associated with the P0167 code include a Check Engine Light, reduced fuel economy, increased emissions, and potentially rough idling. However, in some cases, the only noticeable symptom might be the illuminated Check Engine Light.
Diagnostic Tools: Essential diagnostic tools include an OBD-II scanner to read the code, a multimeter to test the electrical circuit, and a wiring diagram to trace the circuit and identify potential faults.
Troubleshooting Steps: A systematic approach to troubleshooting is vital. Begin by visually inspecting the wiring and connectors, followed by testing the heater circuit's resistance and voltage. Check the relevant fuse and inspect the oxygen sensor itself for any physical damage.
Common Mistakes: A common mistake is replacing the oxygen sensor without properly diagnosing the underlying problem. Thoroughly inspect the wiring, connectors, and fuse before replacing the sensor. Avoid assuming the ECU is faulty without eliminating other possibilities.
Related Codes: Other oxygen sensor-related codes, such as P0137, P0141, or P0157, can provide valuable clues about the overall health of the oxygen sensor system and potentially point to a more widespread issue.
Sensor Types: Modern vehicles typically use zirconia oxygen sensors. Understanding the type of sensor in your vehicle is important for accurate diagnosis and testing.
Heater Circuit Resistance Test: A typical heater circuit resistance ranges between 5 and 20 ohms. Refer to your vehicle's service manual for the exact specifications. An open circuit will show infinite resistance, while a short circuit will show very low resistance.
Heater Circuit Voltage Test: The heater circuit should receive battery voltage (approximately 12 volts) when the engine is running. Lack of voltage indicates a problem with the power supply to the heater circuit.
Potential Repair Costs: Repair costs can vary depending on the specific issue and the repair shop. Oxygen sensor replacement typically ranges from $100 to $300, while wiring repairs can cost between $50 and $200.
Impact on Emissions: A malfunctioning oxygen sensor heater circuit can significantly impact emissions, leading to a failed emissions test. This is because the ECU relies on accurate sensor readings to properly control the air-fuel mixture.
Frequently Asked Questions
What does the P0167 code mean?
The P0167 code indicates a problem with the heater circuit of the Bank 2 Sensor 3 oxygen sensor.
Where is Bank 2 Sensor 3 located?
Bank 2 Sensor 3 is located after the catalytic converter on the side of the engine opposite cylinder number one.
Can I drive with a P0167 code?
While you can usually drive with a P0167 code, it's not recommended. The problem can lead to increased emissions and reduced fuel economy.
What are the common causes of the P0167 code?
Common causes include a faulty oxygen sensor, wiring issues, a blown fuse, or a problem with the ECU (rare).
How do I fix a P0167 code?
Fixing the code involves diagnosing the problem using a multimeter and OBD-II scanner, then repairing or replacing the faulty component. This may involve replacing the oxygen sensor, repairing wiring, or replacing a fuse.
Conclusion
The P0167 code indicates a malfunction in the heater circuit of the Bank 2 Sensor 3 oxygen sensor. Diagnosing and addressing this issue promptly is crucial for maintaining optimal engine performance, fuel efficiency, and reducing harmful emissions. Thoroughly inspect the wiring, connectors, and oxygen sensor before replacing any parts.