96 318ti check engine

P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

P1186 O2 Sensor Heater Control Circuit (Bank 1 Sensor 2) (BMW)

(*) My OBD II list does not have P1185

Since both of these codes are the heaters that are internal to the sensors, I'd start looking at something that is common.

Why did you replace the sensors? What were the codes that prompted you to work on the sensors? Did you reset the codes after replacing the sensors? Did you install sensors that simply plugged in, or did you get the type of sensors that require cutting and splicing wires?

The O2 Sensors have to come up to proper operating temp before they give reliable data. They will eventually heat up as a result of the exhaust stream that is flowing past them, but they have a heater that is built in to heat them up faster. The report you have is that the heaters are not working.

Here is the OBD II reference that I use

hey thanks for the reply..

the first code i had was 0420.

catalyst system efficiency below threshold bank 1. then i bought 2 o2 sensors, and replaced them, then i cleared the check engine lite.

i stayed for about 2 hours then these new codes flashed.

but before i changed the o2 sensors i changed the exhaust system.

so what do you think

I think you are spinning your wheels.

I would not have changed both sensors with the P0420 code, I would have only replaced the one after the CAT. I have too much confidence in the CAT because I think they seldom, if ever, actually fail. And, in the unlikely event they do fail, they clog to the point that you experience drivability problems.

But, it's water under the bridge.

I think -- and I didn't see you address my question earlier -- that you have managed to bungle the wiring somehow, OR you actually have bad heaters in both of your new O2 sensors. Did you get new sensors, or did you go to the junk yard and harvest them from a wreck?

hey man thanks again...i bought them brand new. and i spliced the wires.

2 white wires 1 green 1 black the white wires are for the heaters..thats what i was told. plus they said that it doesnt matter which white one is spliced...

I have no idea what the resistance is on those heaters, but I think you haven't got the wires connected well.

A test that I would suggest is to devise load to mimic the heater, and connect the load directly to the connector on the harness side. This should shut the light off (more accurately, keep the light off after you reset the computer) if the computer is still good. You can test the heater by ohming the white wires.

Personally, I have to wonder if the white wires are really the ones you want. In a typical wiring application, if two wires are the same color, they have the same job -- like being ground. I can't say for certain that this is the case for your car, but I could look in my Bentley manual to confirm, my suspicion.

I'll report back ...

I wou;d bet that this is the source of your problems. I think you have criss-crossed the wires

thanks alot bro...i`ll take them off and try again

According to my Bentley manual, the Engine Management for the '96 ~ '97 1.9L engine has the O2 Sensors configured with BLK, YEL, BRN, & GRN wires. The BLK wire is ground, and the ground on the front sensor is tied to the body of the sensor, but on the rear sesnor the ground is isolated. (I suspect the rear mount is not a qualified ground because it is part of the exhaust system that is isolated from the block via a gasket and rust.) A problem with this ground will affect the data that the sensor generates, it will not affect the heaters.

In any case, the sensor wires are BLK & YEL on both. The BRN & GRN wires are the heater wires. The pin outs are

1. GRN This wire is tied to hot (12vDC).

1. BRN This wire is Heater GND.

2. BLK This wire is Sensor GND

1. YEL This wire is the Sensor SIG

I can't suggest a static test, and you may need one because the wore colors you reported are not the same as in my manual. Frankly, your engine isn't in my manual either -- my book does not show a '96 318 ti. Assuming your ti is the same as the 318, my source should be okay. (There are several references that say, "except '97 318ti," but the O2 Sensors have not got that warning, so they should be the same.)

My gut feeling is that you spliced incorrectly.

hey man thanks alot for the info..but how do i tell what the colors are if mine are different?

and do i disconnect the battery before i remove the o2 sensors

I see no reason to disconnect the battery, the hot wire is only hot if the key is on START or RUN. Just turn the key off and you'll be fine.

I'm not sure how you tell the wires apart, but I think that you have the wires crossed. I NEVER buy the type of sensor that requires splicing. I get the kind that are a direct replacement -- the kind that just plug into the existing connector.

On EVERY instance where the shade-tree guy (you and I) replaced a universal type of sensor, and there was a problem in a week or two, the problem has always found its way back to the shade tree.

were are you from jeff??

im in new jersey.

thanks for your help

California. Just outside of San Diego.

You're welcome.

My computer is in the garage, so I gotta go in because it's getting really cold -- it should drop below 55 soon.

It's colder than I thought. It's below 50 already. With the wind chill, it feels below 50 too. I'll need a fire tonight ...

In this case he was told correctly. The whites are the heater wires.

I wouldn't take that bet.

Whites are heater wires. BTDT back on my old 87 535i (and multiple Volvos of various eras..)