Engine speed (RPM) sensor -G28-, checking

WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Special Tools - Engine Speed (RPM) Sensor -G28-, Checking

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Special tools and workshop equipment required

V.A.G 1526 A Multimeter
V.A.G 1594 A Connector test kit
V.A.G 1598/31 Test box

Component location → Component locations, overview

NOTE: The engine speed (RPM) sensor is a combined speed sensor and reference mark sensor. The engine cannot be started without a signal from the Engine speed (RPM) sensor -G28-. If the signal from the Engine speed (RPM) sensor -G28- fails while the engine is running, the engine will cut out immediately.

Work sequence

Before performing test, make sure that sensor is correctly installed and firmly seated.

Fig 2: Identifying Connectors For Oxygen Sensor

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Disconnect Engine speed (RPM) sensor connector -G28- -Pos. 3-.

NOTE:

Fig 3: Removing Coolant Expansion Tank Bolt

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To gain access to the connector, remove coolant expansion tank bolt (arrow) and move expansion tank to the side. Fuel hoses remain connected.

Fig 4: 3-Pin Connector & Terminals

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Connect multimeter between terminals 2 and 3 to measure resistance.

Specified value: 730...1000 Ω

NOTE: The resistance value of the Engine speed (RPM) sensor -G28- is associated with a temperature of 20 ° C. The resistance increases if the temperature increases.

If specified value is not obtained:

Install new Engine speed (RPM) sensor -G28-.

If specified value is obtained:

Fig 5: 3-Pin Connector & Terminals

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Connect multimeter between terminals 2 and 1 -screen- and 3 and 1 -screen- to measure resistance.

Specified value: each case ∞ Ω (no continuity)

If specified value is not obtained:

Install a new Engine speed (RPM) sensor -G28-.

If specified value is obtained:

Connect test box V.A.G 1598/31 to wiring harness for ECM; do not connect ECM. Refer to Electrical testing using VAG1598/31 test box .

Fig 6: Identifying 3-Pin Connector Terminals 1 & 3

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Check for open circuit, short to positive, or short to ground in following wiring connections:

Connector Terminal	Test box V.A.G 1598/31 Socket
1 (screening)	108
2 (ground)	90
3 (signal)	82

Repair any open/short circuit as necessary.

If no wiring problems are found:

Replace ECM. Refer to Engine Control Module (ECM) (without metal anti-theft housing), replacing .