After another 25,000 km of running (about 45,000 km on the odo), I needed to get the EGR valve cleaned for the second time recently. SVS light was not going off after 4 seconds and MIL light was coming on. Diagnostic investigations at MASS revealed Error Code PO400, i.e., 'EGR Flow'. It was clear that EGR nozzle and / or EGR cooler were clogged and EGR flow was reduced.
I must mention that apart from the warning lights there were NO OTHER SYMPTOMS, i.e., the car was running perfectly at all speeds. I even drove the car on the highway for about 400 km at speeds upto 110 kmph with the warning lights ON and didn't find the slightest difference either in engine performance or fuel consumption.
I got the defect rectified at PEBCO Service Centre at Sonari, Jamshedpur. As expected, both the EGR nozzle and the EGR cooler were clogged with a mixture of soot and oil. The EGR valve itself was not very dirty. Additionally, the Intercooler (after Turbocharger) was also dismantled and cleaned. Cleaning of Intercooler is a part of the 'EGR system cleaning package' at MASS.
The EGR system cleaning package cost me Rs 1520, including a few washers and gaskets that were replaced.