EGR Valve and EGR Temperature Sensor, checking

WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 1999 Volkswagen Jetta, 1999 Volkswagen GTI, 1998 Volkswagen Jetta, 1998 Volkswagen GTI, and 1997 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Checks are made using the VAG 1551 Scan Tool (ST) in "Read Measuring Value Block" function (08), with the engine running at idle (Closed Throttle Position).

Vacuum lines and hose connections free of leaks
Vacuum lines not blocked or kinked
Engine oil temperature at least 50° C (122° F)

Connect VAG 1551 Scan Tool (ST) in "Rapid data transfer" operating mode. Input address word 01 for "Engine Electronics." Carry out selection with engine idling:
See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING

Indicated on display

Fig 1: VAG 1551 Scan Tool Display (Rapid Data Transfer)

Input 08 to select "Read Measuring Value Block" function, and press -Q- button to confirm input.

Indicated on display:

Fig 2: VAG 1551 Scan Tool Display (Read Measuring Value Block)

Input display group number 02 and press -Q- button to confirm input.

Indicated on display: (1-4 Display fields)

Fig 3: VAG 1551 Scan Tool Display (Read Measuring Value Block 2)

NOTE: If the display remains blank: VAG 1551 Scan Tool (ST) operating instructions.

Disconnect vacuum hose from EGR Valve.
Connect VAG 1390 hand vacuum pump to EGR Valve using auxiliary hose.

Fig 4: Connecting VAG 1390 Hand Vacuum Pump To EGR Valve
Operate pump to apply vacuum.
- Idle characteristics must deteriorate noticeably

If the idle characteristics DO NOT deteriorate:

Check lines and connections and clean any that are blocked. If necessary replace EGR Valve.

If the idle characteristics DO deteriorate:

Read EGR temperature value in display field 4. The temperature figure must increase uniformly without interruption.
As soon as the value in display field 4 reaches 200 °C, disconnect hand vacuum pump.
Press ==> button.
Input 06 to select "End Output" function and press -Q- button to confirm input.

If the EGR Temperature value does NOT change:

Check activation of EGR Vacuum Regulator Solenoid Valve -N18-:
See ELECTRICAL TESTING WITH (VAG1598 TEST BOX)

If the EGR Valve clicks during the electrical check:

Replace EGR Temperature Sensor -G98-.
Check Diagnostic Trouble Code (DTC) Memory:
For model years 1993-1995, see DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING

For model years 1996-1999, see CHECK DTC MEMORY (SCAN TOOL FUNCTION 02)