Where is o2 sensor - Cars & Trucks

Heated Oxygen Sensor

• REMOVAL & INSTALLATION
• TESTING

Print

Removal & Installation

3.5L

WARNING When disconnecting the sensor electrical connector, do not pull directly on wire going into sensor.

1. Disconnect the negative battery cable.
2. Disconnect the heated oxygen sensor electrical connector.
3. Use a socket such as a crowfoot wrench to remove oxygen sensor.

To Install:

NOTE When replacing an O2 Sensor, the PCM RAM memory must be cleared, either by disconnecting the PCM C-1 connector or momentarily disconnecting the Battery negative terminal. The NGC learns the characteristics of each O2 heater element and these old values should be cleared when installing a new O2 sensor. The customer may experience driveability issues if this is not performed.

1. After removing the sensor, the threads must be cleaned with an 18 mm X 1.5 + 6E tap. If reusing the original sensor, coat the sensor threads with an anti-seize compound such as Loctite 771- 64 or equivalent. New sensors have compound on the threads and do not require an additional coating. Tighten the sensor to 28 Nm (20 ft. lbs.) torque.
2. Connect the heated oxygen sensor electrical connector.
3. Install the wiring clip to the heat shield.
4. Connect the negative battery cable.
   
   

   Fig.
   

3.8L Downstream Sensor

WARNING When disconnecting the sensor electrical connector, do not pull directly on wire going into sensor.

1. Disconnect negative battery cable.
2. Raise and support vehicle.
3. Disconnect the electrical connector.
4. Use a socket such as a crowfoot wrench to remove oxygen sensor.

3.8L Upstream & Downstream Sensors

NOTE When replacing an O2 Sensor, the PCM RAM memory must be cleared, either by disconnecting the PCM C-1 connector or momentarily disconnecting the Battery negative terminal. The NGC learns the characteristics of each O2 heater element and these old values should be cleared when installing a new O2 sensor. The customer may experience driveability issues if this is not performed.

1. After removing the sensor, the threads must be cleaned with an 18 mm X 1.5 + 6E tap. If reusing the original sensor, coat the sensor threads with an anti-seize compound such as Loctite 771- 64 or equivalent. New sensors have compound on the threads and do not require an additional coating. Tighten the sensor to 28 Nm (20 ft. lbs.) torque.
2. Connect the heated oxygen sensor electrical connector.
3. Connect the negative battery cable.

3.8L Upstream Sensor

WARNING When disconnecting the sensor electrical connector, do not pull directly on wire going into sensor.

1. Disconnect negative battery cable.
2. Disconnect the upper O2 sensor connector.
3. Use a socket such as a crowfoot wrench to remove oxygen sensor.
   
   

   Fig.
   
   
   

   Fig.
   

To Install:

Testing


NOTE Allow the O2 Sensor to cool down before conducting the test. The O2 Sensor voltage should stabilize at 5.0 volts. Raising the hood may help in reducing under hood temps quicker.

1. Turn the ignition on, engine not running. With the scan tool, actuate the O2 Heater Test.
2. With the scan tool, monitor O2 Sensor voltage for at least 2 minutes. Does the O2 Sensor voltage stay above 4.5 volts- If so, sensor is normal.
3. If voltage does not stay above 4.5v as indicated, check wiring and connectors. Check O2 sensor for contamination.
4. If wiring from the O2 sensor is damaged, DO NOT repair it; replace the O2 sensor.
5. Turn the ignition off. Allow the O2 sensor to cool down to room temperature.
6. Disconnect the O2 Sensor harness connector.
7. Measure the resistance across the O2 Sensor Heater element component side. Resistance for either O2 Sensor should be 2.1-2.7 ohms.
8. If the O2 Sensor is not within range, turn the ignition off.
9. Disconnect the O2 Sensor harness connector. Turn the ignition to ON; engine not running.
10. With the proper scan tool, actuate the O2 Heater Test.
11. Using a 12-volt test light connected to ground, probe the O2 Heater Control circuit in the O2 Sensor harness connector.
12. If the test light illuminates brightly and flashes on and off, replace the O2 Sensor.
13. Confirm the repair with the appropriate Verification Test.
14. Turn the ignition off.
15. Disconnect the O2 Sensor harness connector.
16. Disconnect the PCM harness connector.
17. Measure the resistance between ground and the O2 Heater Control circuit in the O2 Sensor harness connector.
18. Is the resistance below 5.0 ohms- If yes, repair the short to ground in the O2 Sensor Heater Control circuit. If resistance is okay, go to step 20.
19. Confirm the repair.
20. If resistance was okay when measured in step 17, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
21. If the resistance is still not within specified range, replace and program the Powertrain Control Module in accordance with the service information.
22. Confirm the repair.

Both codes indicate a a low voltage on the post catalytic converter O2 sensor
Check the wiring to the sensor.
An exhaust leak could also cause these codes to set

Any of the following issues can cause the codes to set
Most likely is a bad connection or faulty O2 sensor

• Air leaks in exhaust in front of o2 sensor giving false reading
• Engine running excessively lean
• O2 sensor connector damaged/corroded
• O2 sensor signal circuit is shorted to ground
• O2 sensor ground circuit is open
• O2 sensor has failed (it may be contaminated with fuel or coolant)
• PCM has failed

If your O2 sensors are malfunctioning, the main symptom would be that the Check Engine light will come on. On some vehicles, an O2 sensor circuit shorted to ground can cause a no-start problem.
If the "Check Engine" or "Service Engine Soon" light is on and there is a code for the O2 sensors, I would like to also advise you that many O2 sensor codes are not caused by the O2 sensors themselves. In many cases, the O2 sensors are only REPORTING the problem. for example, a code P0171 "Oxygen Sensor Lean" code is rarely ever caused by the O2 sensor. It is usually caused by a vacuum leak or a failed Mass Airflow sensor (MAF) or Manifold Absolute Pressure sensor (MAP) or a bad fuel injector. In these cases, repairing the real reason that the engine is running lean will fix the O2 Sensor code without replacing the O2 sensor.

There are several types of O2 Sensor codes. There can be "Lean O2 Sensor" codes, "Rich O2 Sensor" codes, "O2 Sensor Slow Response" codes, or "O2sensor Heater Circuit" codes. The specific code that is being set changes the way you must go about diagnosing and repairing the problem. I will say however, that in about 80% of all the O2 Sensor code problems that I have had to diagnose, the O2 Sensor itself was NOT the problem. The O2 Sensor was only reporting a problem that was actually caused elsewhere. O2 Sensors are the final checkpoint in the engine management system. I think of them like a report card. If the O2 Sensors are right, the rest of the engine management system is right. If the O2 Sensors are not right, the rest of the engine management system is probably not right. (Except in the 20% of the cases where the problem is actually being caused by a failed O2 Sensor)

P0141....O2 Sensor Heater Circuit (Bank 1 Sensor 2)

P0142....O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)

P0143....O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)

P0144....O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)

P0145....O2 Sensor Circuit Slow Response (Bank 1 Sensor 3)

P0146....O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)

P0147....O2 Sensor Heater Circuit (Bank 1 Sensor 3)

P0340....Camshaft Position Sensor 'A' Circuit (Bank 1 or Single Sensor)

To remove the O2 sensor you will need an O2 sensor socket that you can buy at most auto part stores, or you can dis-connect the wire connector for that O2 sensor, and then slip the wire connector from the O2 sensor through a 7/8 inch box end wrench and then slide the wrench up to the O2 sensor and then remove the O2 sensor. Use plenty of W-D40 to soak the base of the O2 sensor before removing it, and if the wire connector does not fit through the box end of the wrench then cut the wire connector off from the O2 sensor, and you will only need the open end of the wrench to install the O2 sensor, and only tighten the O2 sensor up until you feel the the sealing rings crush down, and do not over-tighten the O2 sensor because they are not supposed to be torqued down.

Possible O2 sensors:

P2270 O2 Sensor Signal Stuck Lean Bank 1 Sensor 2
P2271 O2 Sensor Signal Stuck Rich Bank 1 Sensor 2
P2272 O2 Sensor Signal Stuck Lean Bank 2 Sensor 2
P2273 O2 Sensor Signal Stuck Rich Bank 2 Sensor 2
P2274 O2 Sensor Signal Stuck Lean Bank 1 Sensor 3
P2275 O2 Sensor Signal Stuck Rich Bank 1 Sensor 3
P2276 O2 Sensor Signal Stuck Lean Bank 2 Sensor 3
P2277 O2 Sensor Signal Stuck Rich Bank 2 Sensor 3
P2278 O2 Sensor Signals Swapped Bank 1 Sensor 3 / Bank 2 Sensor 3
---
This is Bank 1 (closer to the dash panel) Sensor 2 (located after the catalytic converter).

---
Note: A malfunctioning front oxygen sensor may cause fuel trim codes to set.

1. Several Diagnostic Trouble Codes use specific terminology to refer to sensor location. The illustration and key below explain the following terms:
2. Engine BANK Bank 1 is closer to the dash panel, (also referred to as RH or right hand). Bank 2 is closer to the radiator, (also referred to as LH or left hand).
3. UP Refers to Sensor 1 or "front sensor". It is located closer to the exhaust manifold and before the catalytic converter.
4. DOWN Refers to Sensor 2 or "rear sensor." It is located after the catalytic converter.
5. The following examples show how to interpret oxygen sensor terminology:
6. B1/S1 = Bank 1/Sensor 1 = Dash panel side, BEFORE the catalyst or "upstream"
7. B2/S2 = Bank 2/Sensor 2 = Radiator side, AFTER the catalyst or "downstream"

First what do you mean by a universal o2 sensor? You must make sure that you have the right o2 sensor, most newer vehicles have four o2 sensors 2 upstream and 2 downstream, upstream and downstream are meant to show where the sensors are in relation to the catalatic converter,some o2 sensors have 1 wire or up to 4 wires most with four wires are heated o2 sensors so you need to be sure you ve gotten the right o2 sensor for you vehicle as well as the right replacement for the proper location! My experience is that most after market o2 sensors have the same colored wires as the vehicle. Also most o2 sensors have electrical plugs? If you need help finding the right o2 sensor for your vehicle then please dont be affraid to ask!

That is the oxygen sensor on bank 1 down by the cat converter.