METZGER brand Cooler, exhaust gas recirculation by means of an EGR cooler provides further significant reductions in NOX emissions. Thus, the engine management system is able to recirculate up to 80% of the exhaust gases (depending on the operating mode).

1. TOUAREG (7P5, 7P6)
2. TOUAREG SUV (7P5, 7P6)
3. A6 (4F2, C6)
4. A6 Saloon (4F2, C6)
5. A6 / S6 (4F2, C6)
6. A6 Avant (4F5, C6)
7. A6 Allroad (4FH, C6)
8. A6 Allroad Avant (4FH, C6)
9. A5 (8T3)
10. A5 / S5 (8T3)
11. A4 (8K2, B8)
12. A4 Saloon (8K2, B8)
13. A4 / S4 (8K2, B8)
14. A4 Avant (8K5, B8)
15. Q5 (8RB)
16. Q5 SUV (8RB)
17. A5 Convertible (8F7)
18. A5 / S5 Convertible (8F7)
19. A4 Allroad (8KH, B8)
20. A4 Allroad Avant (8KH, B8)
21. See more in applications

The operation of the EGR cooler

However, in the cold start phase, cooling of the recirculated exhaust gases is undesirable as the combustion temperature decreases. The exhaust gas recirculation cooler bypass valve recirculates uncooled exhaust gases during the cold start phase. Only after the oxidation catalytic converter has reached its maximum efficiency is it switched over to cooling the recirculated exhaust gases in order to reduce the NOX level. For this changeover, the EGR cooler is equipped with an integrated bypass and a bypass flap. During the cold start phase, the bypass opens. The recirculated exhaust gases are bypassed past the EGR cooler. When the calibrated coolant temperature is reached (approximately 45 to 55 ° C), the bypass closes. The recirculated exhaust gases now flow as usual through the EGR cooler.