Ludhiana: Defunct sensors hinder bus operations

Officials say that the malfunctioning of these nitrogen-based sensors has a domino effect on bus operations. Not only does it lead to reduced speed and frequent breakdown but also increases the maintenance costs and spiked pollution levels

The operation of Bharat Stage (BS) VI model buses under Punjab Roadways and PRTC is facing disruptions due to faulty nitrogen-based sensors and a shortage of their replacements. For the last few months, the Punjab Roadways and PRTC workshops in Ludhiana are awaiting these sensors, officials aware of the matter said.

The BS VI buses in Ludhiana. (HT photo)

According to the workshop staff, these nitrogen-based sensors (NOx) are essential for controlling emission levels. These sensors monitor nitrogen oxide in the exhaust and are key to the selective catalytic reduction system, which uses AdBlue, a urea-based solution to turn harmful NOx into safe nitrogen and water. However, when the NOx sensor fails, the engine’s control unit struggles to adjust the emission parameters, often forcing the bus into limp mode and drastically reducing its speed.

Officials say that the malfunctioning of these nitrogen-based sensors has a domino effect on bus operations. Not only does it lead to reduced speed and frequent breakdown but also increases the maintenance costs and spiked pollution levels. With these sensors being critical for adherence to BS VI norms, any deviation or failure in their performance can trigger regulatory action.

Meanwhile, a member of the Punjab Roadways, Punbus and PRTC Contractual Workers Union said that as of now, nearly four out of 30 BS VI Punjab Roadways buses remain out of service at workshops due to dysfunctional sensors.

Praveen Kumar, general secretary of the union in Ludhiana, highlighted,” We are forced to bypass the sensor wiring to keep the buses running. But even then, the buses can cover only 100 to 150 km before requiring another replacement in four days.”

Echoing similar concerns, a senior PRTC official, speaking on the condition of anonymity, stated that sensor failures have led to buses slowing down to 30 km per hour, rendering them unfit for long-distance travel. In many instances, buses have been forced to return to their depots mid-journey, facing the ire of stranded passengers.

Compounding the crisis is the high cost of the nitrogen-based sensors, which range between ₹5,000 and ₹42,000 depending on the compatibility and their supplier. He further stressed that these parts cannot be repaired and needed to be replaced. Since they are an essential component, buses remain out of service until new parts arrive.

Downplaying the crisis, PRTC general manager Praveen Kumar said the issue has been resolved. “We have procured these parts in the last 12 days, and currently, no buses are operating without functional sensors,” he said.