Dear Lamborghinisti,

Arrrrghhhhhhh !

It's baaaaaaack !

Once again, Check engine light O2 Sensor 1 1/6 code P 0133 (sensor slow)


I just don't get it ! I keep getting the same reading on the same d_mn CEL & on my scanner.

I manually check the O2 sensor with my multimeter and the voltage cycles up and down. My scanner also has a real-time analysis and it show the sensor data (properly working).

What should I do now?

I know it's working but I can't stand some little glitch throwing this code. I really really want to get this working PROPERLY !

Any ideas?

I know, I know, I keep beating this horse to death !


Shamile

__________________
Freeze....Miami Vice !

97.5 Lamborghini Diablo VT Roadster
91 Ferrari Testarossa

A Diablo is like a hot tall thin blonde. Sooo seductive, you just keep putting up with her crap. Buying her high-heels or headers, you know she costs you a fortune. But riding her....oh soooo good!

I'd be looking for an exhaust leak. Then maybe a vacuum issue / map sensor.

Have to start assuming the O2 sensor is fine...

-mick

Dear Lamborghinisti,

I forgot to mention, the CEL code P 0133 only comes on with a stone-cold engine start. It comes on if it idles a little too long on start up.

If I start it luke-warm or warm, no matter how long it may idle...no CEL.

Gday, what should I check on the map sensor?

Yes, I also assume the sensor is fine. I keep checking it with my multimeter and it cycles up & down in voltage. My scanner also reads it in real-time as well.

I have changed the vacume lines to the regualors. I was going to change the long lines from the throttle body that run over the intake as well. Any others come to mind?

Shamile

__________________
Freeze....Miami Vice !

97.5 Lamborghini Diablo VT Roadster
91 Ferrari Testarossa

A Diablo is like a hot tall thin blonde. Sooo seductive, you just keep putting up with her crap. Buying her high-heels or headers, you know she costs you a fortune. But riding her....oh soooo good!

If you're only getting a code on cold starts, and everything else is normal, that narrows down what could be going on a bit.

On my 91 there is an additional air valve each side of the engine. When the engine is cold its function is to send additional air to the engine to help adjust the idle.

If one of these was bad, that would likely throw a code that would disappear once the engine started to warm.

Maybe someone else will have some other ideas for you

Hey Y'all,


Thanks Mike.

I was wondering, do you think something could be killing the sensor?

Code P 0133 means bad conditon according to lambo web. My scanner say sensor slow.

When I bought the new one, no CEL code in cold conditons. I just came back from a trip to my other home in GA. 2800 miles round trip, many key starts, very cold mornings (35 degrees ) in GA, no CEL.

Before I bought the scanner, I did the O2 sensor swap. When the 7/12 sensor was put back in 7/12, it threw a bad condition code.

If something was killing the sensor, wouldn't it show up as a different code? Wouldn't throw a "rich" or "lean " code or something like that...ya know, whats killing it?

The sensor is under warrenty, I'm getting another one and will see how long before the CEL comes on.

BTW, the car is a 97.5 Roadster.....so you have 4 sensors. I know the problem lies with cyl 1/6 sensor #1


Shamile

__________________
Freeze....Miami Vice !

97.5 Lamborghini Diablo VT Roadster
91 Ferrari Testarossa

A Diablo is like a hot tall thin blonde. Sooo seductive, you just keep putting up with her crap. Buying her high-heels or headers, you know she costs you a fortune. But riding her....oh soooo good!

Have you swapped the sensor that you suspect is bad for the other side - easy way to tell if the problem lies with the sensor itself.

The sensor is fine. P0133 means that the sensor is not able to track the output swings of the fuel injectors properly. The lambo web is saying the same thing but using older / more technical terms (frequency of change is too low etc). The code is set if the frequency and/or amplitude fall below a preset limit. In later Diablo workshop manuals the words are more standard. Having said that, you would be better off doing as Mike suggests (swap between banks) to convince yourself that the sensor is not "killed" (fault will stay on same bank and no fault on alternate bank).

The sensor downstream only is used to compute pre cat efficiency. Only the readings from the up stream sensor is used to measure what is failing.

-mick

That F'n sucks!

Check for an exhaust leak.

If not, put a pc of black tape over the light! (kidding).

Hey y'all,

Thanks for the info.

Since you mention that the code refers to amplitude swing, I though I would try something.

When going throught the cold start-up, I blipped the throttle once while the carter motor was in it's final stages ( small swings in rpm ) and for some reason this works.

When I have my scanner hooked up in real time, you can see the voltage swing of all 4 sensors. If I blip the throttle, you can see the voltage values swing as well.

It works, no check engine light.

....Now, why does this work?

.....What should it be doing so there isn't any CEL ?

On the question of an exhaust leak, how would I eliminate this question? Do I just listen for a hissing or look for carbon deposits?

On a leak, are we talking only from the manafold to the first cat ( where the O2 sensor is ) or the full run exhaust ?

Sorry for beating the horse to death, but I hate stupid annoying issues.... hmmm, and I keep buying Italian cars ?!??

Shamile

__________________
Freeze....Miami Vice !

97.5 Lamborghini Diablo VT Roadster
91 Ferrari Testarossa

A Diablo is like a hot tall thin blonde. Sooo seductive, you just keep putting up with her crap. Buying her high-heels or headers, you know she costs you a fortune. But riding her....oh soooo good!

Look for leak anywhere...........