P1123
P1123
Oxygen Sensing Adaptation Range 1 (Cylinder 1 - 3) Lean Limit
P1125
Oxygen Sensing Adaptation Range 1 (Cylinder 4 - 6) Lean Limit
Function
The adaptive oxygen sensing corrects longer lasting deviations of the fuel/air mixture from A = 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 > 90°C.
- Intake air temperature < 90°C.
- Air mass flow < 30 kg/h.
- Engine speed < 920 1/min.
NOTE: If DTC P1123 or P1125 (oxygen sensing up to lean limit) is in memory the fuel/air mixture is too rich.
Diagnostic procedure
Check fuel pressure.
1. Remove heater blower at the rear left of the engine compartment.
2. Remove valve cover at test connection of fuel distributor line.
NOTE: Cover must be used only once. Tightening torque: 2.5 + 0.5 Nm
3. Connect pressure gauge P 378 or VW 1318 with attachment line 9559 and connect to test connection.
4. Remove ECM relay (R53) from fuse/relay panel and connect terminals 30 and 87 b with locally made fused jumper cable and trigger fuel pump with system tester.
- The fuel pump should work now.
5. Test values:
Engine not running 3.8 +/- 0.2 bar
Engine at idle 3.3 +/- 0.2 bar
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.