PDA

View Full Version : How to check O2 sensors....



DutchSCFan76
07-11-2006, 11:23 AM
Hi,

How can you test if the O2 sensors are okay?
Car is running lean, popped up during the KOEO test.

Also have a low MAF signal. Are these related to eachother :confused:

Thanks

FredSC
07-11-2006, 12:21 PM
The MAF has a wire running thru it that you can clean (might help). In one thread here, it said use MAF cleaner on a Q-tip but you can probably use a non-residual carb or brake cleaner on the Q-tip (be careful, don't break the wire). Know nothing about O2 sensors.

Bacondoggy
07-11-2006, 12:23 PM
I have gotten the same code on mine. And I haven't been able to fix it. I replaced both O2 sensors too - I used Bosch ones - I have heard some people say they can be bad from the box - I dont know how to tesy them though

DutchSCFan76
07-11-2006, 04:21 PM
Fred, sorry for being a n00b, but what is q-tip :rolleyes:

if you mean the inner- ienny mienny miny small 2 wires, i allready cleaned them, with aceton and a ear-wax stick, to clean your ears with :)

they were indeed filthy....

i guess it got something to do with the CAI i installed from SCP..

LJGriggs
07-11-2006, 04:27 PM
ear-wax stick, to clean your ears with

I think that would be the Dutch equivalent to a "Q-Tip" :D

FredSC
07-11-2006, 04:29 PM
Ahhhhhhhhhh, a Q-Tip is a bathroom item (i think). It has cotton (i think) wrapped around both ends on a paper rod about 2-3 inches long. Another name might be a cotton swab???

oo---------------oo

You can use it for cleaning your ear channel. You can use it dipped in polish remover to remove nail polish. Or you can spray it with carb cleaner and wipe the end across your MAF wire to clean it.

LJGriggs
07-11-2006, 04:45 PM
I can't remember where I got this info, but it might be helpful.

If your car has lost several miles per gallon of fuel economy and the usual tune up steps do not improve it - this *is not* a pointer to O2 failure, it just brings up the possibility. Vacuum leaks and ignition problems are common fuel economy destroyers. As mentioned by others, the on board computer may also set one of several failure "codes". If the computer has issued a code pertaining to the O2 sensor, the sensor and it's wiring should be tested. Usually when the sensor is bad, the engine will show some loss of power, and will not seem to respond quickly.

Testing O2 sensors on the workbench.

Use a high impedance DC voltmeter. Clamp the sensor in a vice, or use a pliers or vice-grip to hold it. Clamp your negative voltmeter lead to the case, and the positive to the output wire. Use a propane torch set to high and the inner blue flame tip to heat the fluted or perforated area of the sensor. You should see a DC voltage of at least 0.6 within 20 seconds. If not, most likely cause is open circuit internally or lead fouling. If OK so far, remove from flame. You should see a drop to under 0.1 volt within 4 seconds. If not likely silicone fouled. If still OK, heat for two full minutes and watch for drops in voltage. Sometimes, the internal connections will open up under heat. This is the same a loose wire and is a failure. If the sensor is OK at this point, and will switch from high to low quickly as you move the flame, the sensor is good. Bear in mind that good or bad is relative, with port fuel injection needing faster information than carbureted systems.
ANY O2 sensor that will generate 0.9 volts or more when heated, show 0.1 volts or less within one second of flame removal, AND pass the two minute heat test is good regardless of age. When replacing a sensor, don't miss the opportunity to use the test above on the replacement. This will calibrate your evaluation skills and save you money in the future. There is almost always *no* benefit in replacing an oxygen sensor that will pass the test in the first line of this paragraph.

DutchSCFan76
07-11-2006, 05:08 PM
Ahhhhhhhhhh, a Q-Tip is a bathroom item (i think). It has cotton (i think) wrapped around both ends on a paper rod about 2-3 inches long. Another name might be a cotton swab???

oo---------------oo

You can use it for cleaning your ear channel. You can use it dipped in polish remover to remove nail polish. Or you can spray it with carb cleaner and wipe the end across your MAF wire to clean it.

hihi, yes then we are talking bout the same stuff :D :D

good for my English too, having this car ;)

Thank you all :)

Next stop to a camping store, for a propane torch :D

FredSC
07-11-2006, 05:37 PM
Here on the island, hardware stores also carry propane torches. They are used when connecting cooper water pipes together.