Volkswagen Workshop Service and Repair Manuals > Polo Mk3 > Power unit | Direct injection and glow plug system with distributor pump as of 10.99 | Fuel preparation system Diesel injection | Checking components and functions | Checking intake manifold temperature sender G72

Checking intake manifold temperature senderG72

Checking intake manifold temperature sender -G72-

Special tools and workshop equipment required

t	Hand multimeter -V.A.G 1526C- or multimeter -V.A.G 1715-

t	Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with diagnosis cable -V.A.G 1551/3-

t	Adapter set -V.A.G 1594C-

t	Adapter cable, 121-pin -V.A.G 1598/31-

t	Current flow diagram

Test procedure

–	Connect fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- and select engine electronics control unit with “address word 01”. Engine must be idling. (Connecting fault reader -V.A.G 1551- and selecting engine electronics control unit → Chapter).

Indicated on display:

–	Press keys 0 and 8 for function “Read measured value block” and confirm entry with Q key.

Rapid data transfer                 HELP

Select function XX

Indicated on display:

–	Press keys 0, 0 and 7 for “Display group number 7” and confirm entry with Q key.

Read measured value block

Input display group number XXX

Indicated on display:

–	Check intake manifold temperature value in display zone 3. The temperature value must be approx. ambient temperature.

–	If a fault is present, a constant intake manifold temperature of approx.136.8°C is displayed.

–	Press → key.

–	Press keys 0 and 6 for function “End output” and confirm entry with Q key.

–	Switch off ignition.

–	If no realistic display appears in display zone 3 or a substitute temperature of 136.8°C is displayed, check intake manifold temperature sender -G72- and line connections to sender as follows:

Read measured value block 7          ->

15.4°C            15.9°C       16.7°C

–	Pull 2-pin connector off intake manifold temperature sender -G72--arrow-.

–	Measure resistance between sender contacts.

Specification see diagram.

Scale A shows resistance values for temperature range 0...50 °C and scale B the values for temperature range 50...100 °C.

Examples:

t	30 °C corresponds to a resistance of 1500..2000 Ω

t	80 °C corresponds to a resistance of 275..375 Ω

If the specification is not achieved:

–	Renew intake manifold temperature sender -G72-.

–	Read fault memory, if necessary, repair any faults and then clear fault memory → Chapter, Reading and clearing fault memory.

If the specification is attained:

–	Connect adapter cable, 121-pin -V.A.G 1598/31- to control unit wiring harness. The engine control unit remains disconnected.

–	Check wiring between adapter cable, 121-pin -V.A.G 1598/31- and connector for open circuit referring to current flow diagram. Contact 1 + socket 73 Contact 2 + socket 54.

Cable resistance: max. 1.5 Ω.

–	Also check wiring for short to one another, short to vehicle earth and short to battery positive.

Specification: ∞ Ω.

If no fault in lines is detected:

–	Renew engine control unit → Chapter.

Volkswagen Workshop Service and Repair Manuals