P1123

P1123
Fuel Trim System too rich TRA (cylinder 1 - 3)
Oxygen Sensing Adaptation TRA (cylinder 1 - 3) Lean limit

Function
The adaptive oxygen sensing corrects longer lasting deviations of the fuel/air mixture of Lambda = 1 through changes of the calculated monitoring within the Engine Control Module (ECM) and with that the injection time. Should the correction factor through adaptation exceed a predetermined value, the diagnosis will detect the adaptation limit.

Diagnosis conditions
- Oxygen sensing is active.
- Time elapsed after engine start-up is 250 sec. to 350 sec.
- Air mass flow < 40 Kg/h.
- Engine speed < 960 1/min.

NOTE: If DTC P1136 (Oxygen sensing up to lean limit) is in memory, the fuel/air mixture is too rich. Always read the DTC memory as it is possible that there are other faults stored in memory which may lead the control to run against the limit.





Diagnosis procedure
Check fuel pressure
1. Remove valve cover at test connection of fuel distributor line.

CAUTION: Cap must be used only once!

2. Connect pressure gauge P 378 or VW 1343 with attachment line 9559 and connect to test connection.
3. Remove ECM relay (R53) from fuse/relay panel and connect terminals 30 and 87b with locally made fused jumper cable. Fuel pump should work now.

Fuel pressure:
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 and check vacuum with vacuum tester.

Engine at idle: 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.

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

- If the fuel pressure regulator is damaged and with that the spring pre-tensioning is increased, replace the fuel pressure regulator.