Cummins ISC Diesel Engine Aftertreatment Code Repair

There’s quite a back story behind this Cummins diesel engine repair. The Thomas HDX pusher was in Surrey on a sports run and everything was going well until the driver phoned me days earlier about an issue concerning the interior heating. The engine temperature was running at a normal level but no interior heat indicating the heat control valve was not working.

Interior heat control valve

We contacted the local school district in the area and they helped us out and repaired the valve. It wasn’t more than a one hour job so it wasn’t a huge burden on them. The agreement among all of the school districts in our province is to help each other out if a bus needs some work.

After that issue we thought happy ending until the driver phoned me back and said the stop engine light came on. This is much more serious than the interior heat issue. I immediately checked the GPS for the bus location and telematics to see what kind of code was activated. It read aftertreatment severe level …. not a good sign when you’re 4 hours away.

This Cummins ISC diesel is a 2009 so it has the diesel particulate filter which I knew from past problems was restricted. The difference in flow from the inlet and outlet was severe enough to derate the diesel engine power. This is one way to get the problem fixed or you’re not going anywhere with this bus. Once I found a tow truck and a shop to have a look at the problem all we could do was wait to hear from them.

On Monday I got a call from the shop working on our bus. They found a restricted EGR cooler and the DPF would require cleaning. However the labor was 18 hours and likely to go up once the job was completed since diagnostic time was not included yet. We decided to tow the bus back to our shop since our labor was much less. I would rather see the problem myself instead of relying on a shop I had never worked with before.

As the video points out the EGR cooler was replaced and the aftertreatment system cleaned out. The difference in horsepower was amazing once the flow restrictions were looked after. This is a regular preventive maintenance that has to be applied to all of our emission controlled diesel engines. This job is not a quick procedure so planning will be important so we can keep up.