avillena

Hi everyone,
Need some help, please! Smog due this Jun 8'20.
I have replaced the following:
MAF
O2 sensors (all 4)
Tried a couple of times to follow the drive cycle to set the monitors, it will last around 90 miles and then engine check pops out (P1123)
I will try to drive the car everyday and hopefully set the monitors before it throws the error code again.
Any other issue that is connected to P1123 code?
I live in San Diego area, if I can't get this to set, can anyone recommend a good Porsche shop where I can take this Targa?
Response will be greatly appreciated.
Thanks,
Andrew

pp000830

Here is the code descriptions, it may help you understand what the code means.
Comprehensive 993 OBD Code List
Andy

pp000830

Driver's side oxygen sensing mixture issue or short to ground
If you are contemplating fixing it DIY and you lack the software and skills to evaluate the oxygen sensor signal:

• I would replace the driver's side (left side) before CAT oxygen sensor as it may be malfunctioning. This is the sensor the computer uses to evaluate for this code. A $60-$80 part if purchase in a Bosch branded box at any auto parts store or online at rockauto.com

• If the issue doesn't go away I would disconnect the battery and reconnect it and take a drive for an hour forcing the Motronic to relearn optimal mixture settings.
• If the problem persists go to the dealer and have them diagnose it for you.

Just what I would do, not a professional technician.
Andy

avillena

I have replaced all 4 O2 sensors; I'll try disconnecting the battery, which I've never done before, and drive it for an hour.
Thanks

71-3.0-911

Once you do that, you'll need to complete the drive cycle, specifically a challenge on the 96 (like mine) and it took 3 tries to get all codes green (I'm told that's normal). The BMW drive cycle posted here worked for me.

geolab

you do not need to drive

the error is calculation of the delta between the pre-oxygen sensor and the post oxygen sensor
if you just changed the oxygen sensors, remove the signaled sensor and check if you have not touched the head with greasy hands.
you should treat O2 sensors like halogen lamps
if dirty ....acetone on tiny brush
then, start car, check obd, if error again, swap sensors left right pre-cat and try again, if error P1125 it's the sensor, if same error P1123 , then it is a story of SAI probably

pp000830

Hi Geolab.
The P-Code description:
P1123 = Oxygen Sensing bank 1-3, short to ground/below lower limit/Lean Mixture Limit;
speaks of mixture being out of normal range I assume is measured by the before CAT sensor alone. How does this involve the after CAT sensor or the delta between the two as the code seems to not have to do with CAT performance? I can see how a contaminated before CAT sensor alone could be the issue unrelated to the after CAT sensor.
Does this make sense or are both sensors used to adjust the mixture for reasons a shade tree guy like me is unaware of?
In any event, as you propose removing the offending before CAT sensor, cleaning it, and putting it back is easy to do, can't hurt and could potentially resolve an erroneous reading.
Andy

shadow993

The front O2 checks the engine, and the 2nd only tells you if the CAT is working.

Put an O2 spacer on post CAT sensor and that will tell you if it's the CaT.

If you got gunk on the sensor, I've been very successful using CDC electronic cleaner.

avillena

I really appreciate all the suggestions and comments; when I replaced all the sensors, I was careful not to contaminate the tip.
Few minutes a go I disconnected the battery and replaced the air filter, will be driving the car this afternoon.
Patience, patience, patience; think this is what I need; I believed I'll get this to set in 3 cycle tries, I hope.
Wish me luck!
Andrew

71-3.0-911

Once he pulls the battery connections he will. Granted, it's unrelated to the code, but if He intends to try and smog it (original post) he needs to complete the drive cycle.

NoRush993/951

I got this same code on one sensor after changing all the O2 sensors. Defective sensor right out of the box.

See the comment at Pelican - changed the sensor and the code was gone. Sent the defective back to Pelican for a prompt credit.
https://www.pelicanparts.com/More_In...I=0876&DID=241

Seems to be an occasional reoccurring Bosch quality issue.

avillena

Hi Folks,
After driving the car for only 79 miles, engine light came on, same code P1123; any other part or parts that are contributing to this error code? could it be SAI?
So, how do I deal with SAI?
If this persist, would a smog referee be another avenue to be able to renew my registration?
Thanks,
Andrew

shadow993

Food for thought to check for bad sensor. Swap it with the opposite side.

il pirata

The shop manual says for DTC 1123 to check, in this order, fuel pressure, then fuel pressure regulator, vacuum connection and return fuel line, then fuel injector for leaks.

Sounds like you will need a good shop. Mirage and Black Forest have been recommended on the forum in the past. Ask if they have the On-board Diagnostic Troubleshooting (OBD-II) Manual. Few do.

As mentioned above several times you could try swapping the sensors as well to see if the code changes.

avillena

Update:
Today, late afternoon, swapped the sensors; drove the Targa for about an hour and registered 66 miles, no engine light. Be driving again tomorrow and see what happens.
If the engine light does not come on, I'll do the drive cycle the following day.
Again, thanks for all the help, stay safe.
Andrew