Exhaust Gas Recirculation: Testing and Inspection

EGR SYSTEM INSPECTION





1. Inspect and clean filter in EGR vacuum modulator.
- Remove the cap and filter.
- Check the filter for contamination or damage.
- Using compressed air, clean the filter.
- Reinstall the filter and cap.

HINT: Install the filter with the coarser surface facing the atmospheric side (outward).





2. Install vacuum gauge.
- Using a 3-way connector, connect a vacuum gauge to the hose between the EGR valve and EGR vacuum modulator.
3. Inspect seating of EGR valve.
- Start the engine and check that the engine starts and runs at idle.
4. Connect LEXUS hand-held tester or OBD II scan tool.
5. Inspect VSV operation with cold engine.
- The engine coolant temperature should be below 47°C (117°F).
- Check that the vacuum gauge indicates zero at 2,500 rpm.
- Check that the EGR pipe is not hot.





6. Inspect operation of VSV and EGR vacuum modulator with hot engine.
- Warm up the engine to above 53°C (127°F).
- Check that the vacuum gauge indicates low vacuum at 2,500 rpm.
- Disconnect the vacuum hose port R of the EGR vacuum modulator and connect port R directly to the air intake chamber with another hose.
- Check that the vacuum gauge indicates high vacuum at 2,500 rpm.

HINT: As a large amount of exhaust gas enters, the engine will misfire slightly.

7. Disconnect LEXUS hand-held tester or OBD II scan tool.
8. Remove vacuum gauge.
- Remove the vacuum gauge, and reconnect the vacuum hoses to the proper locations.





9. Inspect EGR valve.
- Apply vacuum directly to the EGR valve with the engine idle.
- Check that the engine runs rough or dies.
- Reconnect the vacuum hoses to the proper locations.
If no problem is found with this inspection, system is normal; otherwise inspect each part.
10. Cancel diagnostic trouble code.