OBD 2 error code P1123
 

Hello,
I have 1999 Porsche 911 carrera and have Error code P1123.
here is a detail from the scaner.( O2S Sensing Range 1 Cyl, 1 - 3).
Any idea?. I did replaced ALL 4 new 02 Sensor. PLEASE HELP, this is my first Porsche. Thanks. SmileWavy:D

Another example of “throwing money at the problem” rather than diagnosing what the DME is telling you……… There is nothing wrong with any of your 02 sensors, probably never was.

P1123 indicates an over rich condition on one cylinder bank (cylinders 1-3) that the 02 sensor and DME fuel trims cannot adjust for, usually caused by either a leaking injector or excessively high fuel pressure.

Hello JFP in PA,
I strongly agreed with you about throwing good money away. I do really regret getting 4 new O2 sensor and after all the original O2 sensor is still good.
So, how could i check for leaking injector and high fuel pressure?
Please help, I don't want to throw a good money away and i am really frustrated cause my car failed smog test and the registration is due.

Thanks

Specific tools are needed to do either. You would need to pull the injectors and examine and test each one in order to find which one(s) are bad. Fuel pressure is done by connecting an injector system fuel pressure gauge to the test port on the fuel rail and testing it with the car off and running. Pressure (engine not running) should be 3.8 +/-0.2 Bar; running it should be 3.3 +/-0.2 Bar.

nphra... a couple of suggestions. You might want to post your location so maybe someone could recommend a trustworthy indy shop that can diagnose correctly and fix your problem before you run out of time for your renewal. Sometimes you just need to do that and you might find you spend less money in the long run. At the same time you learn more about the car and become educated about what you can do and where your limits are.

Unplug the sensor (Item 3 is the sensor). Remove the two T20 security Torx screws (Item 4). Replace the sensor and tighten screws. Plug electrical connection back in.

http://forums.pelicanparts.com/uploa...1329016051.gif

Changing the MAF will be yet another waste of money, he has an overly rich fuel mixture on one bank only; the MAF cannot casue this to happen on only one cylinder bank at a time...................

I'd test MAF with a volt meter and the MAF appear to be in great shape and function property. I also clean the MAF with the electrical cleaning solvent.
My next thing to do before taking to the shop is clean the fuel injectors with injector cleaner. I don't know if i be able check for leak injector as JFP mention.
Please advise me if you know any thing about this issue.
Can it be my aire filter?

Oh..FPB111, thanks for the drawing.!

Thanks

What really funny is that the engine light never came but the scan tool tell error codes, P1123 and P1125.

How soon did they come back after you cleared them? Maybe a fluke?? Not likley but if you have the tool it is free.

Hi FPB111,
After reset the error codes (P1123 and P1125) will reappear in about 20 to 100 miles. (or when ever the driving cycle met).
The engine light didn't come on though.
Where should i look for fluke and tool?.
My last last last thing to do is take the car to the dealer and have them check for leak injectors and fuel pressure test.

Oh...one of the porsche certified repair shop told me that its the Evaporative Purge Valve Canister.
He also say that since the car running smoothly it cannot be a leak injector or fuel pressure.

I will try any things
Please advise me.

Thanks

Will replace the MAF tommorrow and will post the rersults.
Nothing to loose.
Replaced all 4 O2 sensor. $326
Replaced Vaporator purge valve. $129
Next is MAF. $76

after replaced the MAF code P1123 and P1125 is gone but P1127 and P1129 comes on. any idea beside taking to dealer..?
You feedback is greatly appreciated.

Thanks
nphra

Try to find another independent garage rather than the dealer ($$). If you are getting close to or are past 100,000 miles then don't feel bad about the O2 sensors, they usually need to be replaced aroud that time.

Thanks for the reply KNS,
I did replaced all 4 O2 sensor, Evaporator purge valve and MAF.
and now i'm gett P1127 and P1129, before i replaced the MAF i'm getting P1123 and P1125. Now the P1123 amd P1125 is gone.

My next task is leak test but don't have any test tool.
Any idea will be great appreciated.

Thanls

Today P1129 goes away and P1127 comes on.
What's really going on ? The car drives soo smooth though.

P1123 fuel pressure adapter
 

I have been getting P1123 a few times and would like to follow JFP's suggestion and start with a fuel pressure test. I looked into the Actron but they would not sell the gauge and adapters into Canada and have not found a Canadian source. Internet sources I have contacted do not sell the adapter. Have looked at Snap On but the dealer cannot suggest which adapter would work with their Gauge. Anyone have an idea.
Our Boxster is a 98 with about 45,000 miles and runs great.
Thanks Ron in Ontario

Hi Ron,

You might want to try posting in the Canada forum in the Regional section. There's a fair number of folks in Ontario, but I'm unsure where you are. Perhaps someone out your way can help you.

I'm not 100% sure if the 98 Boxster uses a proprietary diagnostic port or if it uses OBD-II, but if it uses OBD-II, Snap On's MODIS should work assuming you have the Porsche/Euro module loaded. The Snap On MODIS diagnostic tool isn't cheap (I've looked into this) so I am a firm believer a small investment into a Durametric scan tool will pay off quickly.

Mike

Fuel Pressure Test
 

Hi Mike
I have the Durametric program. What I am after is information to connect to the test port on the fuel rail to test the fuel pump output pressure. My Snap On Rep gave me a list of EEFI adapters but none suit a Schrader valve.

Regards
Ron

Oh, sorry! I totally misunderstood!

I'm afraid I don't have the answer to your question. Good luck!