SEAT Workshop Service and Repair Manuals > Leon Mk2 > Power unit | 4LV Injection and Ignition System | Mixture preparation system, electronic inj.,Gas | Function test | Lambda probe and pre-catalyst lambda probe: testing

Test the lambda probe wiring

–	Connect test box -V.A.G. 1598/31- to the wiring harness of the control unit, without connecting the engine control unit.

–	Test for open circuits in the wiring between the test box and the 4-contacts connector, following the wiring diagram. Contact 3+female contact 52 Contact 4+female contact 71 Contact 5+female contact 70 Contact 6+female contact 51 Wire resistance: 1.5 Ω max.

–	Following the wiring diagram, test the connector wiring contacts 3 + 4 for short circuits to contacts 1 + 2.

If no fault is found in the wiring:

–	Replace the pre-catalyst lambda probe -G39-.

–	Press 0 and 8 for the function “Read measurement value block” and press Q to confirm the entry.

The display reads:

–	Press 0, 3 and 3 for “Display group number 33” and press Q to confirm the entry.

Read measurement value block HELP

Enter display group number XXX

The display reads: (1...4 = display fields)

–	Watch the lambda regulation in display field 1. The value should oscillate 2 % minimum within the range:

- 10.0...10.0 %, -15.0...15.0 %

–	Watch lambda probe voltage in display field 2. The voltage should oscillate at least 20 times per minute within the range:

0...1.0 V, 0.3...0.6 V, oscillating

Read measurement value block    33    →

1            2            3            4

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