O2 SENSOR and CEL ELIMINATOR (1 Viewer)

[MTBGUY]

Hello to all-

I recently cleared the PO420 code :shotts: another time after a few months without it. I looked at some of the other postings on here, but my question is not solved by those posts.

A local (trusted) exhaust place looked at my 80s' exhaust and said it looked really solid with very lttle corrosion for an almost ten-year old car, that spent 7 years in NY. They told me that the 420 code is generated 90% of the time by the second (rear) o2 sensor. He said these Cats will last forever and most problems are due to the gaskets or O2 sensors.

Questions:

1) I replaced my old O2 sensors with the "generic" splice in Densos (Ebay- $25). The exhuast guy said that many generic splice in ones will throw codes more often than the one you buy from Toyota. Anyone have opinions on this? It looks identical to the Denso one I pulled out of the car. Or are they just trying to get me to buy another one from them?

2) They checked for leaks around the gaskets in front and behind the Cats with a "sniffer" type tool and found no leaks, even though the middle gasket is looking pretty old. Do these "sniffers" work pretty well, or would they detect a very small (or occasionally in cold weather) leak?

3) A friend told me of a splice in (DIY) wire kit called a CEL/MIL eliminator that you can put inline with the rear O2 sensor. He says it will cancel the CEL that gets set off occasionally by the rear sensor, but still allow the front one to work normally and is not bad for the environment or the car itself. He says that 1995-1997 OBD2 cars are especially prone to the PO420 codes thrown from the rear sensor due to the fact that OBD2 wasn't yet perfected at the time.

Thoughts anyone? Has anyone ever used the MIL eliminator, or had any problems with the generic O2 Denso sensors.

I already bought them and used them, but next time it will be factory Toyota parts from Cdan to avoid this stress.

Cheers!

 

[Bruneti]

Short version:
Either re-install your splice-in sensor making sure to properly solder and heat shrink the connections, or buy a new Plug&PLay OEM Toyota/Denso O2 sensor from C-Dan and install it yourself.
It only makes financial sense to use a simulator if you completely remove your cats, or if they are shot and you are leaving them in place for some reason(?).

Long tech explaination why:
I have an O2 sensor simulator installed on my '97 Supra Turbo. I put this on after removing both factory cat's and putting in a 3" mandrel bent SS downpipe to eliminate the restrictions. I purchased the simulator direct from casperselectronics.com (they are usually the supplier for the ones you see sold at various performance shops on the net). It works very well if you understand what it really does, and the new version that they sell for Toyota does not require any cutting and splicing since it uses oem style connectors to put it in-line with an existing O2 sensor. This part is very important, so please read carefully. You DO still need an O2 sensor with a functioning heater installed in the circuit. The O2 sensors that are used have a heating coil in them to bring them up to operating temperature faster. The factory ECU monitors the O2 signal AND the resistance of the heater circuit. If either goes out of range for a defined period of time, it will throw a code. The O2 sensor simulator only interrupts the O2 feedback circuit to provide the O2 analog signal in a range acceptable to the ECU. You still need a sensor in place with a good heater to provide the proper resistance back to the ECU to avoid a code. So - since you still have properly functioning cats, and since you still need a (partially) working O2 sensor, and since a simulator costs about $80 anyway, it makes more sense to me to pay the smart shopper price (probably only $30 more than the simulator) to C-Dan and fix it right and be done. Hopefully you now see that the black box does not entirely "replace" the O2 sensor. It could if they would incorporate a resistor of the appropriate size into it, but I'm sure the heat it would generate could pose a liability issue if it started a fire in someone's vehicle.


Here's a link to the O2 sensor simulator for Toyotas:
https://www.casperselectronics.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=104057&Category_Code=toyota

 

[Scamper]

Not to mention that without functioning O2 sensors, you will be running rich or lean at different times since the ECU will not know if it's pumping too much or too little fuel. I'd replace with OEM.

 

[MTBGUY]

Thanks guys

 

[RavenTai]

Questions:

1) I replaced my old O2 sensors with the "generic" splice in Densos (Ebay- $25). The exhuast guy said that many generic splice in ones will throw codes more often than the one you buy from Toyota. Anyone have opinions on this? It looks identical to the Denso one I pulled out of the car. Or are they just trying to get me to buy another one from them?

So far that has been the experience of everyone who has tried cheap universal O2's

cDan was right! OEM O2 sensors are better. if you compare to Scotts other threads the bosch universals were weak.

Discounted OEM O2's from CDan seam to be the only guaranteed "get it right the first time" product so far.


Cats can go bad, mainly being poisoned by contaminants but I would not replace them until you are sure you have good 02's.

Simulating the rear O2 Does not affect mixture, mixture comes from the front O2 on 95-97 OBD2 80 series.