Change o2 sensors as PM or check with scan tool

[ford46guy]

Of course the manufacturers like to say to change your o2 sensors at X number of miles, but if you can verify that the sensors are switching properly does that really make sense?

The PCM of course watches them like a hawk but you can check them with a scan tool. Can the pattern though detect subtle degradation?

 

[Linctex]

Originally Posted By: ford46guy

The PCM of course watches them like a hawk but you can check them with a scan tool. Can the pattern though detect subtle degradation?


The ECM is well aware of the subtle degradation issue, and will flag a CEL when the switching rate becomes too slow.

The ECM actually tests response by making the mixture slightly rich or slightly lean on purpose, and then notices how long it takes for the HEGO's to react.

If within parameters, no CEL.... if the test fails, CEL comes on.

 

[86cutlass307]

Originally Posted By: Linctex
Originally Posted By: ford46guy

The PCM of course watches them like a hawk but you can check them with a scan tool. Can the pattern though detect subtle degradation?


The ECM is well aware of the subtle degradation issue, and will flag a CEL when the switching rate becomes too slow.

The ECM actually tests response by making the mixture slightly rich or slightly lean on purpose, and then notices how long it takes for the HEGO's to react.

If within parameters, no CEL.... if the test fails, CEL comes on.


Well put...if you have access to or can look up the resistance values in the diagnostic section of a / your factory service manual they usually recommend a certain temperature to check resistance at. You can run them until you get a light or if resistance values are approaching the limit either high or low; I choose to replace early if the weather is warm. You never know what might go wrong.

 

[Trav]

I change them as PM if the opportunity arises on an otherwise very difficult to get at sensor. I did exhaust manifolds on a Ford 5.4 2V these would be a real PITA to get at but with the pipe down and manifolds off it was easy access, with almost a 100K on them I swapped them.

 

[Leo99]

hmmm, I've never seen a PM recommendation to change out an O2 sensor. At least not with my Toyotas. I just change them out when the CEL comes on indicating a possible O2 sensor problem.

When I was troubleshooting a code a couple years ago, I hooked up Torque Lite and analyzed the wave forms to verify the sensor was on the fritz. That proved ambiguous. It didn't look like either the good waveform or bad waveforms I compared it to online. I think the ECM is better about telling if the sensor is working properly than I am with an inexpensive scan tool.

When I've had the CEL come on for an O2 sensor, the engine still ran fine so it's not like you'll be stranded on the side of the road. I don't see any point to worry about them. They can last a long time.

 

[WobblyElvis]

I have a 2006 4 cylinder ecotec engine that sometimes hesitates. More so when the engine has not warmed up yet. The O2 sensor is original with 180,000 miles. I have cleaned the MAF sensor and changed the plugs. No CEL and I cannot find any vacuum leaks. I have read that a hesitation is a sign of a worn O2 sensor.
Any opinions on this? I don't like to replace a part and find no joy in it.

 

[daman]

PM it.

 

[Trav]

Originally Posted By: Leo99
hmmm, I've never seen a PM recommendation to change out an O2 sensor. At least not with my Toyotas.


Years ago VW had a 30K flag that come up on the instrument panel. Back in those days we did lots of cats (pellet cats) and O2's a year at 30-50K.

 

[Linctex]

Originally Posted By: WobblyElvis
More so when the engine has not warmed up yet. .... No CEL and I cannot find any vacuum leaks. I have read that a hesitation is a sign of a worn O2 sensor.


Not likely, if the engine hasn't entered "closed loop" mode yet.

 

[WobblyElvis]

Originally Posted By: Linctex
Originally Posted By: WobblyElvis
More so when the engine has not warmed up yet. .... No CEL and I cannot find any vacuum leaks. I have read that a hesitation is a sign of a worn O2 sensor.


Not likely, if the engine hasn't entered "closed loop" mode yet.


That's a good point. Now... if I could only find the real problem.

 

[SHOZ]

You can watch the voltage output on the O2s to see if they are good. But if you have no codes then they probably still are good.

Resistance would only be for the heater.