OBDII Diagnostic Trouble Code P0150 can cause your Infiniti to run rough, get poor gas mileage and even make it hard to start in the morning. Today we’ll be looking at how to test a Infiniti QX4 oxygen sensor in a 2003 Infiniti QX4 with a VQ35DE engine in it. The specific verbiage for the P0150 trouble code is 02 Sensor Circuit Malfunction (Bank 2 Sensor 1).
Because this specific OBD-II trouble code details the oxygen sensor on Bank 2, this is for the driver side of your VQ engine. Bank 1 refers to the side of the engine that cylinder #1 sits on, and in this engine, cylinder #1 is located in front of the passenger side of the engine.
The part number for this oxygen sensor is 22690-4W021, and there’s a few Nissan / Infiniti interchange part numbers, which are 22691-4W003.
Sensor 1 refers to the front 02 sensor, or the upstream oxygen sensor. Because your VQ35 relies on this air fuel reading to accurately adjust your fuel delivery in your 3.5 liter V6, P0150 can cause some serious driveability issues.
Causes for OBDII DTC P0150
- Lazy or slow front 02 sensor
- Bad or failed front 02 sensor
- Problem with wiring or wiring connectors
Before you begin our how to test a Infiniti QX4 oxygen sensor DIY guide, you’ll need to locate your Bank 2 sensor. Open your Infiniti QX4 hood and locate your primary Bank 2 oxygen sensor by following the passenger side header until you find the 02 sensor.
Unplug the oxygen sensor, which is a three pin weatherproof connector. Once you’ve pulled this sensor connector, you’ll need a multimeter to finish learning how to test a Infiniti QX4 oxygen sensor. Put your multimeter into Ohms mode Ω and you’ll be measuring the resistance in the 02 sensor itself to see if it’s still good.
In order to complete this part of the test, make sure your oxygen sensor is cold or at least at room temperature. Nissan calls for this sensor to return a value between 2.3 to 4.3 Ohms (Ω) at 74º F. To read the resistance of your front VQ35DE oxygen sensor, put the terminals of your multimeter on PIN 1 and PIN 3
You should see a resistance value between this range for this sensor. If you find your resistance is outside of this range, you will need to replace your primary Nissan 02 sensor to resolve the P0150 check engine light.
Next you will be checking for continuity between PINS 1 and 2, as well as PIN 2 and 3. Continuity should not exist at these terminal pairings, if there is, your upstream oxygen sensor has failed and must be replaced to turn off your trouble code light.
Ok, so far we’ve tested the resistance of the oxygen sensor as well as testing for failure through continuity. If your P0150 OBDII trouble code still isn’t going away, chances are you have a break between the front primary oxygen sensor and your QX4 ECU.
If your trouble code isn’t going away, and your passenger side (BANK 2) oxygen sensor has passed all of our how to test a Infiniti QX4 oxygen sensor DIY guide, there’s a good chance you’ve got a problem with your ECU wiring.
This means that someplace between your oxygen sensor and your ECU, there’s a short or break in the wiring. Not to worry, we’ll be using the multimeter to check for continuity between the terminating VQ35 ECU wiring and your 02 sensor.
Here’s what you’ll need to do to complete the job of testing your Infiniti QX4 wiring for any shorts or breaks.
- Disconnect the negative terminal of your battery
- Unplug your upstream passenger side oxygen sensor (Bank 2)
- Locate and disconnect your Infiniti QX4 ECU
- Test for continuity between terminal #2 of the 02 sensor and Terminal 50 of your VQ35 ECU. If continuity exists, go to step 5
- Test for continuity between terminal #2 of the 02 sensor and Terminal 51 of your VQ35 ECU.
- Test for continuity between terminal 2 and an engine ground.
If you have continuity through all the tests, then this means your Bank 2 oxygen sensor wiring is not at fault. You can replace your primary oxygen sensor and use a scan tool to clear your OBDII P0150 trouble code in your Infiniti QX4. Test drive your vehicle to make sure that you’re trouble code free.
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