O2 Emulators or simulators???

Hey all....99 silverado 4x4 Z71 149,000 miles I have had a p0420 code for a while and had it posted here. I have checked everything from vacuum leaks to bad o2 sensors. I have swapped my o2 sensors (after the cat) and clear the code. The code comes bad as a p0420. So I know that my o2 sensor is not causing the error. I have just replaced the tranny for $2000.00 and don't really have another $500.00 to put into this truck right now.

Has anybody heard of a O2 emulator or simulator? They are for plugging into the after cat harness and giving the ecm the proper readings. They run for about $40-$45 bucks and beats $500.00. This will get me by for the holidays. My truck goes in for emission testing by the end of December.

Other than emmisions, if this o2 emulator can give the ecm a good reading, how would this relate to performance or gas mileage, if I decided to keep it on there for a while longer??

the cat is most likely shot...at what mileage did you replace the upsteam O2 sensors????

If these sensors are the original this usually means the cat is cooked..I don't know how you will get to trick the emission test ...

the O2 SENSORS ARE RATED FOR 100,000MI...after that you risk cat failure....

It's not likely the oxygen sensors are at fault for the P0420 as they are tested and would set a DTC BEFORE the P0420 monitor is run. The sole purpose of the downstream oxygen sensor is to monitor the efficiency of the converter. It does not affect the running of the engine. It will however, illuminate the SES light after running the monitor for the converter, if you install any kind of simulator. When the ECM runs the monitor, it must see a change in voltage from the sensor at a precise time. PM me with your email address and I will send you the diagnostic flow chart for P0420, if you'd like.

the cat is most likely shot...at what mileage did you replace the upsteam O2 sensors????

If these sensors are the original this usually means the cat is cooked..I don't know how you will get to trick the emission test ...

the O2 SENSORS ARE RATED FOR 100,000MI...after that you risk cat failure....


I have never replaced any o2 sensors as of yet 149,000 miles

Update.....This may help others...

I did get a o2 simulator and it did get rid of my 0420 code. But within 5 days, my CEL when on agian....no not a 0420 code but a 0171 and a 0174. I thought is was that fact that I was low on gas, but I cleared it and came back again. I finally had a time this weekend and cleaned the whole engine with gunk. I then waited for it to dry and then sprayed carb cleaner to check for a leak....no leak.
(no difference in RPM changes) I then pulled the pvc and checked for a vacuum in the engine case ( I was told that the intake gasket could fail on the inside and pull the pvc for a check there) But I then replaced the Pvc valve. I started the motor and the CEL light was off, and I did not clear it. It cleared itself. Truck runs real smooth at idle and in drive. I can feel a difference when I get on it.

Hey check the PVC and replace for $2.

Will keep updated. If I can keep the CeL of for a week, I will pull the simulator and see if that was the problem...

many have never replaced the pcv and this part on later models i think 2005 on up do not have a replaceable pcv as you and I do.

this part with the hoses are the componets to be checked when getting these codes TOGETHER...

the use of carb cleaner is not recommended...over time the rubber/plastic componets will fail...

your oil leak with the PCV issue this may be related...the pcv maintains a slightly negative crankcase pressure, with this valve not operating correctly the crankcase MAY have had a positive pressure, this will cause leaks....