96 tracker p0136

[gorkyb]

Car seems to drive normally however this code is stored, o2 sensor is only a few months old

[gorkyb]

Car seems to drive normally however this code is stored, o2 sensor is only a few months old

Looking at the OBD2 scan, it looks like the O2 sensor after the CAT is bad, it is stuck at 0.04V, it is not hunting. I see RockAuto differentiates sensors between upstream and downstream, I used the same Bosch downstream as I put upstream when I did work on the exhaust, am I using the right sensor downstream?

[fixkick]

what code?

Car seems to drive normally however this code is stored, o2 sensor is only a few months old

Looking at the OBD2 scan, it looks like the O2 sensor after the CAT is bad, it is stuck at 0.04V, it is not hunting. I see RockAuto differentiates sensors between upstream and downstream, I used the same Bosch downstream as I put upstream when I did work on the exhaust, am I using the right sensor downstream?

the rear 02 should not hunt. (if the cat is good) That hunting in front 02 is the AFR in closed loop mode,, hunting constantly for perfect AFR. Sthoch.
the rear 02 signals are very complex set of rules.

the sensors are different.
the rear sensor is only a CAT monitor, the cat will burn all excess fuel and oxygen, as it exits the cat. a completely different usage.

if the ECU sees the Rear 02 hunt it knows the cat is missing or rodded out. or totally dread. (or bypassed)
and throws DTC 420 to warn you of that fact, called the Lazy cat failure.

here is my 02 sensor buy page
http://www.fixkick.com/sensors/OxyGen_se...#oxy-parts

i cover the front only in my matrix table.
but the bosch tables are clear.
4 sensors. 2 for PNP and 2 for Universal (bare wires)
http://www.boschautoparts.com/VehiclePar...inder.aspx

[gorkyb]

Luckily my Tracker passed inspection for another year last week, before this started happening. I will get the proper O2 sensor for downstream, Bosch 13035. Thanks for the info.

[fixkick]

420s DTC?
lazy cat, wrong 02, there, ,or bad 02 there,. or air leaks there.

it looks for lazy signal (no swing, just drift at no oxy, no oxgen there.
Some newer cars ,even this car, (very hard to prove there or not) have smarter 420 monitors that prevent hacking.
some folks found that unscrewing the O2 rear, then putting it in jail (lol) that is into a blank bung fitting that is capped off and no oxygen inside (all illegal) will fool the 420 monitor
but later they added code in the monitor to check the CAT when its cold , and the shocking discovery that its missing because when cold there is oxygen present.
not saying to do this but am saying the rear sensor is a tricky monitor on most cars and for sure newer.

a hot cat burns the tiny excess HC and this consumes all oxygen too. leaving NOx and CO, and CO2.
The rear sensors is only to find bad Cats.

but like all sensors they go bad or air leaks near it cause it to lie. air is 20% oxygen (sealevel) and the 02 will go quite nuts with 1% leaking to it. dont take much is my point..

now watch the most funny video ever (a man of my heart here)

what i do is make it leak free, (cracks)
and the core is not missing (look)
then get CAT real hot with long hot fast 60mph drives. (fast flat cruise in STOICH mode, eg HOT)
clear 420s first then see if it comes back, ive got many a dead cat to wake up, not even touching it.
if that fails
then scotty to the rescue.

http://www.youtube.com/watch?v=5icTmYItwiE

he offers 2 ways, and knows, that some cats can be repaired.

I like the soap and water fix.
i wonder if a trip to the car wash with the cat in hand would work. or would the high pressure crush the honey comb..
?

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my wild guess, is the down stream sensor is more sensitive to oxy. (im sure Bosch tells this. but haven't found it yet)

---

the Oxy sensor is also differential. sensor.
it has outside air ports.
and it measures the difference from inside to outside. , i say that because mud or grease can clog the outside.
the bosch sensors, do this in a very genius way.
instead of visible ports on body, (slots or?) they hide it in the connector end of the body, wired end , has the ports, well hidden and real hard to clog. Bosch makes great sensors, and invented it.

it is just a very hot, tiny battery inside.
not to mention, it must get hot, many sensors, the heater is dead, or the 12vdc to the heater, is dead. your newer car reports this very well, if bad heater current.

[gorkyb]

no 420's stored at all, just the P0136. Its output does not change ever from the 0.04v

[fixkick]

at least.
the PNP sensors are different because the wires are different lenght, and the connector may be keyed differnent too.
the universals are different. but why not just have 1 wire length ,if that is all the difference
one great response i saw is why, do the job twice, the books shows the correct parts.
the rear universal sensor has 0.4 inches shorted wires. (surely this is not the only difference, that be crazy, to box those up just for that....)

btw many folks find using the same sensor front/rear do Seem,work ok.

things (params) that can vary is the speed the sensors responds. or warm up time. or other parameters being different.
keep in mind if it is sensitivity? , then the wrong sensor might be running ok now, then the monitor 420 later cries wolf, telling you the cat is weak , too soon.

just because something seems to work , does not make it good, it must work correctly under all conditions, even in Alaska, or in desert.

[gorkyb]

this could explain also why I was having 420 CEL's before even though the CAT I have there is fairly new and the car hasn't been running out of normal specs. The downstream sensor also bring the rubber fitting that seals the wire going through the floor of the car to connect under the driver's seat.

[fixkick]

136
sensor to is reading wrong. (my guess is air leaks)
the sensor is averaging wrong, below 120mv 0.120 vdc or above 0.9vdc
or
the connector is bad and the voltage jumps to 4.5v for 2 seconds.

the voltage will drift from lean to rich, as the front sensor is in closed loop.
basically it means the cat is missing, air leaks or cat is bad, or connector loose.
i dont think its your sensor.
but im still contacting bosch for that big question. why are they different (universal versions),

[gorkyb]

You're right, I should check the connection before I buy anything. it could just have come loose or something. Thinking about it, this is most likely what it is since the readings never change from 0.04v