P0167 code definition
O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 3)
What P0167 code means
Many oxygen sensors are heated now in order to bring them to operating temperature more quickly. If any of the wiring in the heater circuit for this oxygen sensor is damaged this trouble code may appear.
What are the causes of the P0167 code?
- Damaged wiring in the heater circuit
- Faulty oxygen sensor
What are the symptoms of the P0167 code?
When the engine is first started, the engine’s fuel system is running in what is called “open loop”. During “open loop,” more fuel is used to keep the engine running (a rich condition) due to the fact that the air/fuel ratios are running on a pre-determined specification programmed into the powertrain control module by the manufacturer.
When the oxygen sensors have heated up to operating temperature, they begin to produce a signal voltage that is sent to the powertrain control module. When this happens, the engine goes into “closed loop.” This is where the powertrain control module will adjust the air/fuel ratio based off of the readings given by the oxygen sensors. If the heater circuit for the oxygen sensor is damaged, the sensor may never reach operating temperature causing decreased fuel economy and bad emissions.
How does a mechanic diagnose the P0167 code?
A mechanic would likely start the diagnosis of the P0167 code by taking a look at the third oxygen sensor in the second bank of the exhaust to check for any burned or damaged wiring coming from the sensor.
This is the most common cause of this code. If the wiring for the circuit looks fine, the problem likely lies in the sensor itself.
At this point, the mechanic would then test the oxygen sensor for proper function using the manufacturer’s specific procedure. If the sensor turns out to be functional, the problem lies in the powertrain control module.
Common mistakes when diagnosing the P0167 code
Just like any other trouble code that uses the words O2 sensor, the most common mistake that could be made in this circumstance would be to replace the oxygen sensor as the first step.
Some people think that, just because “oxygen sensor” is named in the trouble code, then this means that the part will automatically need to be replaced. This often leads to a misdiagnosis and wasted money.
How serious is the P0167 code?
The P0167 code can be lived with for a short time. Considering that this code is related to the third oxygen sensor in the second bank of the exhaust, the powertrain control module should still be receiving a signal from the five other oxygen sensors.
With the signals remaining, the powertrain control module should be able to maintain a correct air/fuel ratio for a period of time. It would still be wise to have this problem diagnosed and repaired as soon as possible.
What repairs can fix the P0167 code?
- Replacing the oxygen sensor
- Repairing wiring associated with the oxygen sensor heater circuit
- Replacing the powertrain control module
Additional comments regarding the P0167 code
The powertrain control module is a rare failure and everything else should be confirmed to be functional before replacing the powertrain control module. The most common causes of this trouble code are a faulty oxygen sensor or damaged wiring associated with the heater circuit of the oxygen sensor.
Need help with a P0167 code?
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This article originally appeared on YourMechanic.com as P0167 OBD-II trouble CodeO2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 3) and was authored by Andrew Quinn.