P0133 Only @ Highway Speeds

[David325e]

Got an SEC code shortly after getting the car. pulled the ground strap on the battery and counted to 20. HAven't seen anything since. I originally thought it was related to hitting the speed limit. Been about 2wks and a couple thousand miles.

Today I was on the highway for about 30 miles, longer than I've been since the first light. Speeds between 55 and 80. Got the service engine light again. Sure enough, P0133 again.

Sounds like a bad cat? I have no smell or visible symptoms. But it's the only other thing I can think of that'd throw Bank 1, sensor 1 only on the highway. I'll flog on it tonight and put the car on the lift to see if the left side is glowing.

I'm doubtful that it's an air metering issue. The car is the best idling BMW, possibly car, that I've owned. Stays at a solid ~750, goes up just a nudge with the AC on. And In my mostly city driving I'm returning 17-18mpg.

-Dave

[sigtwenty]

It says slow response as the code. Usually low response is pretty much saying the sensor is shot.

Now if you were getting lean codes or rich o2 codes then I'd look at leaks or fuel issues.

On the freeway there is more air flowing thru the exhaust and the readings are not registering fast enough to keep up with spec so the dme is saying hey I see readings and the readings are within range but I'm not getting enough readings at the right speed.

Now a lean or rich code for example means the sensors are reading a condition caused by say a vacuum leak causing an increase in air in the air fuel ratio.

So three things I'd be checking.

1. Wiring to that said o2 sensor to make sure insulation isn't burnt.
2. Battery and alternator output voltage. Since no other codes or driving issues are present I'd rule this out. But worth a check.
3. Most likely, the oxygen sensor is shot.

The cat would have different codes and thrown off from the post cat o2 sensors.

[David325e]

The man
The myth
The legend.
Sig20.

I appreciate it buddy. I'd forgotten about the lean/rich/slow differences. Been about 5+ years since I owned an obd2 car.

I'll check into the wiring. I think voltage is good. Picked up a free meter yesterday to keep in the truck. I was comparing it to the fluke different places. 12v on my battery, and 14.2v with the engine idling.

02 isn't covered by the warranty. I have about 10 bosch sensors in boxes ,time to start cross checking PNs haha.


Edit: hopefully tonight I'll get over to pick up the comprehensive service records. In the warranty papers there's a mention "trimming of catalysts"

[David325e]

Back TTT.

The temperature has started to drop here. The yesterday I went on an extended drive. Moderate speeds, 40-60, but no stoplights for a good 40 minutes. The CEL went off and didn't come back on. Checked the codes, nothing. The temperature was about 60. Not so cold, but 40's the night before and really dry air. I was driving windows up, air off.

Today, it's back to 80 and humid. Get in the car this morning and run around town, nothing. Get onto the highway, and about 5 minutes go by before the light is on.

I noticed something else yesterday when it was cool. I was coasting down a fairly steep hill to a stop. Foot on neither pedal, rolling from ~50mph down to a stop. Before I started braking she was hunting for idle. Between ~750 (normal) and 1400. Didn't do it again. Waiting for the woman last night I had the seat laid all the way back. At idle there was just the slightest bit of shake or lump. Not noticeable with the seat up.

I have no symptoms of a hanging ICV. I do have a check coolant level light only when I park at a severe upwards angle at one spot in my parking garage. No other time. Do I remember that the valley pan gasket is just a coolant leak? Start checking icv piping, intake boot, valve cover gaskets? What say ye geniuses.

[IcemanBHE]

Whats the code for the light?

Sounds MAFy to me.

Edit: See the code in the title.

Statement stands.

[David325e]

Get out of here with that dirty talk :stickoutt


But really, even with just one side signaling? Good to know, I'll look into it. I think I might have a MAF in the box still.

[IcemanBHE]

Not sure...

But thats what popped in my head.

And I didnt read the whole thread...one side not working is not good.