is there a way i can test me o2 sensor if it's still good? my truck is throwing a code 41

41 No HEGO switching detected always lean (right side).


what does this mean? does this mean my o2 sensor is dead? how do i test it to see if it really is dead?

 

I think there is check the chiltons

 

If it is a 3 wire sensor 2 are probably for the electric heater and the other is for the power generated from the sensor itself which the computer uses to trim the ejectors. Find out from a wiring diagram which one it is. Carefully remove the weather pack from the back of the picktail connector so you can touch the wire connector with the positive lead on you digital multimeter and the the negative lead to a good ground preferbly the battery neagative post.Set the meter on the 20 volt setting. With the sensor heated up it should toggle from .100 to .800 volts at least 3 times a second

 

autozone.com says

No attempt should ever be made to measure the voltage output of the sensor. The current drain of any conventional voltmeter would be such that it would permanently damage the sensor. No jumpers, test leads or any other electrical connections should ever be made to the sensor. Use these tools ONLY on the PCM side of the wiring harness connector AFTER disconnecting it from the sensor.

http://autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0a/2c/3d/0900823d800a2c3d.jsp

wtf?

 

Pre-test conditions:
Single wire, Run engine at 2000 R.P.M. for 3 minutes before starting test. O2 sensor does not become fully operational until approximately 650 degrees Fahrenheit, below that it will give low voltage signals. This also ensures vehicle is in "closed loop".

Multiple wire, If more than one wire is present then sensor is equipped with a heater to ensure faster operation of O2 sensor. Normally a warm up time of under a minute is necessary.

Test Procedures:
1. Through the use of a break out box or backprobing, tap into the O2 sensor signal wire with a D.V.O.M. or lab scope. Note: Never use any type of analog meter on an Oxygen sensor!
2. Install test equipment with (+) side on O2 sensor, (-) side on battery negative. (or an alternate good ground source)
3. With vehicle off, key on you may see 450 millivolts at sensor or at vehicle harness with sensor unplugged, this is normal.
4. Ensure engine is sufficiently warmed up.
5. Note voltage readings, should be fluctuating from above 450 millivolts to below 450 millivolts, fairly rapidly. Usually falling to about 2 to 300 millivolts before heading back up to between 6 to 750 millivolts. 450 millivolts is the perfect number the computer is trying to stay at so it’s constantly "switching" in an effort to maintain this.
6. Run engine at 2000, voltage fluctuations should remain but the rate speed at which they occur should increase. If it does not it’s faulty. A lazy O2 sensor
7. Snap throttle wide open, then release, if engine accelerates normally O2 sensor should rise momentarily to 900 millivolts minimum, then fall below 100 millivolts and return to normal. If it can’t reach 900 millivolts (weak) or doesn’t fall below 100 millivolts (lazy), it’s faulty. Note: exhaust must be voltage drop tested if a single wire sensor fails to read under 100 millivolts. Should be under .050 volt drop.
8. Readings should not rise above 1.1 volts for any reason, If they do then you have a faulty O2 heater. It is leaking electrically into the O2 sensor circuit, causing higher voltages that would normally not be possible.

Run these test anytime an O2 sensor code has been set or you suspect a problem with the O2 sensor. If it passes, chances are the O2 sensor is O.K. and you should look elsewhere for the problem. The O2 sensor is commonly replaced during trouble code diagnostics when it is not the cause of the problem! Diagnostic trouble codes that report an overly rich or lean mixture are commonly caused by failures other than the O2 sensor, such as state of tune, fuel system problems, other sensor failures and the list goes on and on. We use these tests to verify that the O2 sensor is not the cause of the problem!

 

I have the same problem with code 41 and my brand new O2 sensor isn't switching... for instance it responds to opening and closing of the throttle meaning the voltage changes but it doesn't oscillate.

Maybe I fried it. I had the O2 sensor connected and probed the wires with an analog voltmeter on the harness side of the wire. What exactly is backprobing... how do I know I am doing it right?

I'm still getting the 41.

Suggestions?

Thanks,
Todd

 

Todd, backprobing refers to sticking the pobes from your meter into shell of the connector to touch the pins on the ends of the harness while the device is still hooked into the circuit as opposed to unplugging it for a check of the wire itself or to see if voltage is present. Depending on how & what you're trying to check. Some connectors are sealed on their backside and there is no way to slide the probe under the insulation or heat shrink to get to the connectors pin for the test. One way is to peirce the wire "ever-so-slightly" with a straight pin then connect your meter to that. The problem with this is that 1), it can change the resistance and hence the value of what you're trying to read 2), you must re-seal the tiny hole with a dab of scilicon (water & corosion will result) & 3) repeated testing can weaken the wire.

 

Basically if you're chasing an O2 sensor code it's best to just replace it, don't forget to clear the codes afterward. If it comes back then you need to UNPLUG the sensor and test the wiring between the PCM and the sensor harness. If that checks out good then check your grounds from the batter to the engine, frame, and body. Make sure that the wires are in good shape, and where they bolt up are clean.

 

i agree just replace with a ford (motorcraft) o2 sensor. many including myself have had issues using the cheaper autozone or schucks o2 sensors for what ever reason.

 

Hey thanks for the info... so I was doing it right. I will do what you all told me to do and let you know!


Thanks