silverporsche993

Yesterday it was around 100 F (index of 110f) and the temp gauge was just over the 1/2 mark-- which id unusually high. But considering the outside temp and humidity was still in an ok range. I drove for about 45 minutes and then the CEL light came on and p1123 was the code. I reset it and seems ok this AM. Would the extreme heat set it off? Thinking I might need an oxygen sensor if it triggers again. I did a search on p1123 and not much came up on the 993 list.

thanks peter

axl911

It's the O2 sensor.

Here's a list from my notes of the codes.

DTC Circuit Or Condition
1000 End Of Output
1111 Power Supply Wrong Voltage
1112 Ground In Idle Speed Control Circuit
1113 Ground In Full Load Contact Circuit
1114 Open Engine Temperature 11 Circuit
1115 Idle Control Interrupted
1121 Air Sensor Flow Circuit
1123 Oxygen Sensor
1124 Oxygen Sensor
1125 Air Temperature Sensor
1131 Knock Sensor 1
1132 Knock Sensor
1133 Knock Regulation Circuit
1134 Hall Sender Signal
1141 ECU
1151 Fuel Injector No. 1
1152 Fuel Injector No. 2
1153 Fuel Injector No. 3
1154 Fuel Injector No. 4
1155 Fuel Injector No. 5
1156 Fuel Injector No. 6
1311 Fuel Injector No. 1
1312 Fuel Injector No. 2
1313 Fuel Injector No. 3
1314 Fuel Injector No. 4
1315 Fuel Injector No. 5
1316 Fuel Injector No. 6
1321 Idle Speed Control Circuit
1322 Tank Venting Solenoid
1323 Resonance Flaps
1332 Idle Speed Contact
1333 Full Load Contact
1334 A/C Activation
1335 A/C Activation
1500 No Faults Stored

DTC Circuit or description
11 Supply voltage
14 Engine temp sensor 2
16 Throttle potentiometer
17 0il temperature sensor
18 Rpm signal
19 Speed signal -Speedometer
21 Air flow sensor
23 Oxygen regulation
24 Oxygen sensor
26 Ignition timing change
27 Opening winding of idle stabilizer
28 Closing winding of idle stabilizer
29 Activation of AC relay
31 Knock sensor 1
32 Knock sensor 2
33 Control unit faulty
34 Hall signal
35 VarioCam
36 Idle CO potentiometer
41 Control unit faulty
42 Fuel pump relay (DME-relay)
43 Tank ventilation
45 Check Engine warning lamp
51 Injection valve cylinder 1
52 Injection valve cylinder 2
23 Injection valve cylinder 3
54 Injection valve cylinder 4

LH Diagnostic codes

11
Supply voltage

12/15
Idle speed contact

13
Full load contact

14
Engine temperature sensor II

21
Air mass sensor

22
Idle speed control activation

23
Oxygen regulation stop, rich

24
Oxygen regulation stop, lean

25
Oxygen sensor, open circuit

31
Injection circuit shut down

41
Control unit faulty


EZK Diagnostic codes

12
Idle speed contact

13
Full load contact

14
Engine temperature sensor II

15
Idle or full load contact

21
Load signal LH

26
Transmission protection switch

31
Knock sensor 1

32
Knock sensor 2

33
Control unit faulty (knock sensor)

34
Hall signal

41
Control unit faulty

C4S993

I get that 1123 code a lot, just clear it and drive another 500 to 3k and again it pops up. Trick is to make sure the sensors are all ready for Pa Emission Inspection; minus the 1123 code of course. Replaced all but one of the 4 O2 sensors; the 4th original sensor is welded in the CAT after 175k miles !
1996 C4S