Technical Description of OBD-II Trouble Code
Malfunction in the O2 Sensor Heater Circuit (Bank 2 Sensor 3)
What does this mean?
This code is a generic powertrain code that applies to all makes and models of vehicles (1996-newer). However, the specific repair steps may vary slightly depending on the model.
O2 (Oxygen) sensors have a heating element that allows them to quickly reach operating temperature. This helps reduce emissions by enabling the engine to enter closed loop faster and stay in closed loop at idle.
The heater circuit receives a 12 V battery feed from the PCM or ignition circuit (depending on the model) and a ground. The PCM (powertrain control module) monitors the time it takes for the sensors to become active after engine start-up. If the o2 sensors take too long to reach operating temperature, this P0167 code can be triggered. Bank 2 refers to the side of the engine that does not contain cylinder #1.
Symptoms
For this specific O2 sensor, there may be no noticeable symptoms other than:
Causes
Possible causes of a P0167 code include:
Possible Solutions
1. Unplug the Bank 1, 3 sensor. With KOEO (key on engine off), use a voltmeter to check for battery voltage at the o2 sensor connector (PCM side). (You can also use a test light for this. Connect it to ground and touch the lead to the heater circuit supply. The light should illuminate with KOEO) Battery voltage should be present.
a. If voltage is present, check the ground side of the heater element to ensure a good ground is present. If it is, check for any faulty connections and then replace the o2 sensor. If a good ground is not present, there may be an open in the ground circuit that needs to be repaired. Look for any contact between the wiring harness and exhaust components or any broken/missing connectors.
b. If battery voltage is not present with KOEO, check for a blown fuse supplying the heater elements. You may need to refer to a wiring diagram for this. If the fuse is blown, check for a short to ground on the battery supply circuit before replacing the fuse. If no short is found and replacing the fuse restores battery voltage at the o2 sensor connector, then the o2 sensor may have internally shorted, causing the fuse to blow. Replace the o2 sensor and recheck. (NOTE: It is possible for an o2 sensor’s heater circuit to be open/shorted and still function properly).
c. If there is no battery voltage present with KOEO and no blown fuses supplying the heater circuit, check for an open in the supply circuit. You can do this by measuring the circuit’s resistance with the o2 sensor and PCM unplugged. Repair any open circuit and recheck.
