P1123

P1123
Oxygen Sensing Adaptation Range 1 (Cylinder 1 - 3) Lean Limit.

P1125
Oxygen Sensing Adaptation Range 1 (Cylinders 4 - 6) Lean Limit.

Function:
The adaptive oxygen sensing corrects longer lasting deviations of the fuel/air mixture from lambda = 1 through changes of the calculated pilot control within the engine control module and with that the injection time.
Should the correction factor through adaptation exceed a predetermined value the diagnosis will detect the adaptation limit.
Range 1 covers the engine operating state close to idle.

Diagnosis Conditions:
- Oxygen sensing is active.
- Time elapsed after engine start-up is 250 to 350 seconds.
- Engine temperature > 62°C.
- Intake air temperature < 90°C.
- Air mass flow < 29 kg/h.
- Engine speed < 880 rpm.

NOTE: If DTC P1123 or P1125 (oxygen sensing up to lean limit) is in memory, the fuel/air mixture is too rich.

Diagnostic Procedure:




1. Checking fuel pressure.



1. Undo covering cap on test connection of fuel collection pipe and remove.
2. Connect pressure gauge (special tool P 378a) with connecting line (special tool 9559) and connect to test connection.



3. Actuating fuel pump

- with Porsche System Tester 2.
The fuel pump can be actuated with the Porsche System Tester 2 or by bridging the fuel-pump relay.

- via fuel-pump relay without Tester. Disconnect fuel-pump relay from the central electrical board and bridge contacts 30 and 87 (identified as 3 and 5 on the central electrical board) with a fused shop-made cable. The fuel pump must now operate or deliver fuel.

4. Nominal test values:

Stationary engine: 3.8 ± 0.2 bar.
Engine idling: 3.3 ± 0.2 bar.

NOTE: The seal or sealing ring in the brass closure cap is not exchangeable. It must therefore be used only once.

Tightening torque of new brass closure cap: 2.5 ± 0.5 Nm (2.0 ± 0.5 ft. lbs.).

2. Check fuel pressure regulator, vacuum connection and fuel return line.
1. Remove vacuum line at fuel pressure regulator.
2. Connect special tool 9103/2 to vacuum hose.
3. Start engine.

Display: 0.4 - 0.6 bar.

If the value is not reached, check vacuum system for leaks and check vacuum line to fuel pressure regulator for restrictions.

4. Check housing of fuel pressure regulator for outside damage.

Replace the fuel pressure regulator if the fuel pressure regulator is damaged with the result that the spring pretensioning is increased.