threw p0135 *sigh*

[fuzzy1]

Ok, so mine threw CEL... advance auto's cheapy code reader says p0135... o2 heater circuit failure...
What do I test to see if the wiring is good or if i need a new o2 sensor? The sensor was obviously replaced shortly before I bought the car, & I haven't looked at it, since it hadn't been a problem. I'll be visually inspecting the connections today, but any advice on testing is appreciated. Thx in advance.

Fuzz

[jtgh]

HO2S Heater Circuit Malfunction Bank 1 Sensor 1


can only be 3 things.
bad sensor
bad wires (conn.)
bad ECU. (not likely)

the sensor heater can go out at any time. (even water splashing up on it causing rapid coolilng of heater and internal cracking)

or it could be a victum of lean running. over heated.

the ECU makes sure the heater draws proper current.
if below spec, the ECU throws 135.

you can.
inspect the connectors and wiring , for damage, burns , chafing. etc.
you can measure the current with an ampmeter.
you can power it up with power supply 12vdc ( test battery) and measure the current on a bench.

If the ECU says its bad, I believe it. (just like Ivory soap, 99.9999% pure)

its just a heater, and as such can be easily tested.

i think its 1amp draw normal, and if lower by 50% , the DTC throws.
IN THE FSM, all the steps to test it.
and online at your pub. lib. (usa)

IIRC, but yours will be most likely open circuit, and 0 amps draw.


cheers.

[jtgh]

spec.

> 4.0 amps (shorted 02 heater)
< 0.22 amps (open or weak)

can throw if battery drops below 10v. but youd have lots of other symtoms.
or Alternator goes berserk and goes over voltage. (regulator slammed to over charge)


page , 6e3-a-80 FSM

13 steps for the tests. in FSM
(blown fuse is one)
first test if for checking power to the o2 connector, key on, o2 removed.


o2 sensor , heater resistance
is
11.7 to 14.3 ohms (not K ohms) at room temp.

id check that first just to dispell , obvious replaced , issue.

[fuzzy1]

Hehe, thx Jerry... x3... you must have been replying to others at same time? But, guess that's what I needed to hear.
It wouldn't surprise me any if the replacement part was el-cheapo brand x given other PO related things I've found.
I did a visual inspection, wires appear good, & the replacement sensor does have the proper 4 pin connector.
Just for the sake of knowing, which pin is heater circuit power? & where to check the impedance? I guess I'd like to test just to be sure before I throw a new Bosch in it. Thx again.

Fuzz

[jtgh]

amazing your answer is right here. (sorry browser hung)
http://www.kick-fix.com/ECU/1996/EFI3.jpg

my schematic page has 96 , page 1 ,2 3.
page three, bottom left. is O2

the car schematic shows harness colors.
there are 5 mfg. of sensors and each colors their wires diff.
if you need actual sensor colors tell me mfg of sensor.
bosch, denso, etc.

or just plug it in and cross correlate the colors to above schem.

just tell me old sensor mfg name

[fuzzy1]

Well, just to update: Sure enough the sensor was bad, good news is it came out easily. Replaced with a Bosch, which came with anti-seize compound on the threads, yay!! Pulled the dome fuse... CEL gone. Hardest part was removing the heat shield from the manifold... odd that it blocks access to the 'nut' on the o2 sensor. I thought of trimming it so it wouldn't in the future, but then I figure this 1 should last a long time so meh... Also good news is my manifold isn't cracked!! Still low miles though, so *knocks on wood*.
The o2 sensor that was in it doesn't have a brand name on it that I can see, it only says:

Japan
5360
09B25

2 black, 1 white & 1 blue wire.

Anyhow, all better now, thx for input.

Fuzz

[jtgh]

thanks for feedback ?
later tell us MPG you get.
FYI and others.
they make a special o2 sensor deep well socket 3/8"drive, sold dirt cheap at harborfreight.
make short work of all them.

yes, the Bosch is a great sensor. very good.

my suspisions are that not fixing car when sensors bust, cause it to go to limphome. (it does do that)
then when you drive hard, the manifold glows red hot. (i will in Limphome for sure )
same with ignoring EGR bad.

the EGR actaully cools the valves and the manifold.
most think its bad (was in 80s) but not now. it is our little helper due to smart ECUs.

cheers.