Tip & How-To about Cadillac DeVille

How to Test the O2 Sensor of Cadillac Devile car?

O2 sensor needs to be replaced when you get low gas mileage in car.
So before replacing the sensor it needs to be tested.
The procedure to test O2 sensor is as follows: ---
1) First drive the vehicle for 15 minutes in normal temperature.
2) Then Stop the vehicle in park mode and turn the engine off.
3) You will see primary O2 sensor on the exhaust manifold, the manifold will be very hot to touch so take care.
4) The function of O2 sensor in the car is to measure the amount of oxygen in car and then send that information to engine to adjust fuel pressure.
5) Now to measure the O2 sensor reading. Carefully disconnect the wire at the O2 connector, and hook the positive lead of volt meter to the O2 sensor side of the connector and connect the positive lead of volt meter to harness side of the connector.
6) In the O2 sensor you will notice two black wires that are not used for testing.
7) Now before beginning the important part of the testing procedure, check out properly that wires of O2 sensor and wires of volt meter are not getting touch to any other metal part or the manifold.
8) After checked and confirmed. Now start the car and see the voltage in engine idle position.
9) The reading will go high or go low but the average reading that it should show is 500 mV.
10) Now let the engine run and with engine running disconnect the fuel pressure regulator vacuum hose, and plug the hose with your finger.
11) The 500 mV reading will go to 700-800 mV.now remove the finger the reading will fall low to 300 mV.
12) But if these readings are not showing properly that indicates the fault in the sensor.
13) The secondary O2 sensor is located after the catalytic converter. The procedure to measure secondary O2 sensor is exactly the same like how you measured the primary O2 sensor.
14) The secondary oxygen sensor is located under the car.
15) Put the car on jack stands on the rack, this will give you proper sensor location in the car.
16) You can test secondary O2 sensor to conform the fault before replacing the O2 sensor.
17) The cost of replacing the O2 sensor is near to $100.This cost is for if you do it yourself.
This will help. Thanks.

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1 Answer

We have been having horrible gas mileage but the other day All of a sudden the car hesitates, sputters and dies when trying to go into gear.. I was thinking the fuel pump? I have to replace the o2 sensor, mass air flow sensor, and another I cannot remember the name of! Help please!


You replace nothing

You learn how sensors work & how to test
them

They only get replaced when they fail a test

O2 Sensors get replaced at 100,000 miles or
when they fail before that mileage.

Your best to let a repair shop diagnose & solve your
problems. It will be cheaper than throwing parts at it

May 23, 2011 | Toyota Paseo Cars & Trucks

1 Answer

what causes my nissan maxima to get low gas mileage? I was told the sensor bank one and had ti replaced no change in mileage.my gage jumps from 12 -27 miles a gallon.It drinks gas!


Driving habits...incorrect tire pressure...excessive weight in car...low oil/old oil. Many things affect mileage. My 2002 max needed a new O2 sensor. Once replaced the mileage improved slightly.

Sep 06, 2010 | 2002 Nissan Maxima

1 Answer

2001 Montero Sport does not have power when climbing mountain pas


Considering what has been done, the problem sounds like a fuel issue. Do a fuel pressure test, it should be 47-50 psi with vacuum line pulled off fuel pressure regulator. If low replace filter and try again. If still low replace pump. Please make sure to rate me when done. Thanks

Jun 08, 2009 | 2000 Mitsubishi Montero Sport

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