P0150 - O2 SENSOR CIRCUIT MALFUNCTION (BANK 2 SENSOR 1)

The voltage on the oxygen (O2) sensor is based on the amount of oxygen in the exhaust. Its voltage changes between 0.1 and 0.9 volts. 0.1 volts would be a poor condition and 0.9 a rich condition.

When the circuit is closed, it is monitored by the Engine Control Module (ECM), which is responsible for establishing the amount of injected fuel. If the ECM (Engine Control Module) signals that the O2 (Oxygen Sensor) voltage is below 0.4 volts for a time of 20 seconds (although the time varies according to the model), the fault code P0150 OBD2 will be set. This code refers to bank 2.

• The check engine light is on.
• Fuel consumption is higher than normal.
• Engine instability.
• Black smoke coming out of the exhaust pipe.

When the P0150 code is set, it might mean that:

• The O2 (Oxygen Sensor) connector may have water or corrosion.
• The terminals of the connectors may be loose.
• The exhaust components may have a burned-out wire.
• A cable may be short-circuited by rubbing against a motor element.
• The exhaust can have holes, therefore, there is unmeasured oxygen in the exhaust.
• Vacuum leaks.
• The oxygen sensor may be defective.

To solve the diagnostic code P0150, you could do the following:

• By using the scanner of your choice, determine whether the oxygen (O2) sensor in bank 2 is working properly, i.e. whether it is switching from the rich to the poor mixture properly. This should be done quickly and evenly.
• If it does, it indicates that the problem may be in the sensor wiring. That's why you have to move the connectors and wiring system around while watching the voltage on the oxygen sensor. Repair or replace it if you see inconsistency in one of these.
• If the sensor does not change the mixture correctly, examine and determine if the reading given by the O2 (Oxygen Sensor) is accurate in the exhaust. To do this, remove the vacuum from the fuel regulator since the reading given by the sensor must be rich, due to the fuel that has been added. Return the vacuum to the regulator, it should have a poor condition there. If the sensor is working properly, the problem may be caused by some holes in the exhaust pipe or vacuum leaks. If it is a hole in the exhaust, it is due to the sensor that does not read properly because of the extra oxygen coming into the exhaust pipe through the holes. If it is a vacuum leak, this is usually accompanied by other diagnostic codes.
• Make sure the oxygen (O2) sensor has a 5-volt reference.
• Check the 12-volt circuit power.
• Check the continuity of the ground in the ground circuit.
• Repair if in any of these the voltage is not appropriate or any cable is short-circuited.
• If the voltages are within the specifications, you could change the oxygen (O2) sensor.