Foolishness

Hey guys I'm not really new to the forums, I've been lurking for sometime now and just made a account recently after I picked up my 4runner. It is a 96 v6 manual 4x4 sr5, with just under 150k miles on it.

So When I bought the car the previous owner said he had to replace the o2 sensor a few weeks ago, which I got under the car and look to see and it was a new sensor(after the cat). after driving it around I get a CEL which happens to be p0136 which is a malfunction in the o2 heater circuit.

I did a search on here and it seems like people just get a o2 sim to get rid of the code. my mpg seems to be fine, I'm getting around 17ish for city and hwy. I was wondering how would I check if the cat if its bad or not? also is it likely that a bad front o2 is causing the code for the rear one?

I didn't bother to check the freeze frame data the first time around because I figured the new o2 was still breaking in. but the second time the cel came up I wrote it down.
here are the areas where it actually had values

Load% 42.4
ETC (F) 199
ShrtFT1% 0
LongFT% 5.5
RPM 1811
VSS(MPH)14
IAT (F) 93

DailyDrive

First things first, you should take a close look at the waveform the sensor is putting out. Then go from there.

p.s. looks like you are running hot @199F. Thermostat is 190F.

Foolishness

I'm use to pinning from the diagnostic port in the engine bay. but there doesn't seem to be pins it the ox1/2 slots. Is there a way to check this w/o getting under the car with the car on? or a fancy obd2 reader?
also I got under the car to double check if the new sensor was the one after the cat and I noticed that the sensor is a bosch with a flange on it. And from what I've been reading denso is the only way to go. Should I just go ahead and order a new denso one?

DailyDrive

I'd hardly call OBDII readers fancy, they go for $10-20 shipped on Ebay.

Bosch might not be recommended, but I'd test the current sensor first with OBDII. You do need to see what is really happening first.

OBDII to a mechanic is what a thermometer and a stethoscope is to a doctor.

Foolishness

I ordered the cable the day I got the cel. the tracking said it should get here this week or the next. But in the mean time I got the code several times now after clearing it. it seems to show up mainly on city driving. but I have another car so I stopped driving the 4runner for now. also when I was looking at the freeze frame data my temp is always at 199 degrees when the code is thrown.

rworegon

There are numerous threads about these engines not liking the Bosch O2 sensor and kicking the CEL on. Stick with the Denso brand sensor.

Order from:
http://www.trdparts4u.com/Scripts/default.asp
http://www.densoproducts.com/

TheDurk

Heater circuit means heater circuit. it's a fault in the heater or the associated wiring, including the connector plug. Front sensor has nothing to do with it. Being Bosch should have nothing to do with it as long as the resistance of the heater is within spec. (I agree Denso's work better but on P0136 it should make no difference.) Check heater resistance and voltage to the heater before and after the connector.

rworegon

Also, check the O2 sensor circuit wires for frays or a melted spot that is shorting out.

Foolishness

before I jump in and start testing I just want to double check and make sure this is the right one i'm testing.

TheDurk

Probably not. I see Air/Fuel mentioned on the circuit diagram which means that diagram is from a '99-'00 Cali. spec. or '01+ 50-state model. Two cats, wideband air-fuel sensor in front, etc.

Yours is a '96 one-cat, standard O2 sensor front and back. I am pretty sure the wire colors and pin-outs are quite different because the ECU is quite different. You can still test for voltage at the sensor. First test the sensor heater resistance. If that checks out, test the heater wires for voltage to chassis ground with key on, sensor unplugged. One should have 12v+, the other (return to ECU) nada. Then plug in sensor. Key on again. Both wires should have 12V+ before and after the connector.

If that all checks out, then you can go worry about the ECU plug pin-outs.

Foolishness

thanks for making sure. I just started my new full time job which they were nice enough to work with my school schedule. So between work and full time school I dont have very much time during the week days. I'll take a look at this when the weekend comes around. if there is there anything else I would look into?

Foolishness

So my cable came in... I ordered a usb one and the disc was cracked during shipment so I've been trying to get the drivers for them. It also doesnt help that I'm on a mac but I can easily setup vbox for xp. Can anybody point me into a direction of which software I should get for this that would enable me to look at sensor data? As there seems to be a lot of them but I dont know which one actually works for our cars.