P1C54

[jelag]

About 2 years ago my truck when through the recall where the rear Nox sensor and controller were removed from the truck and the software was upgraded....Along with the associated hard parts... (sorry, can't remember the recall #) during the next 6 months the truck was seen 7 times for the original mechanic failure in that he didn't follow the instructions on the recall.... he removed the Nox sensor but left the controller connected and caused the DEF system to over inject and damage the SCR.... The factory authorized a complete redo of the recall replacing all the related hardware again.....

I had troubles getting the shop to actually look at what the first mechanic had done until I contacted CUSTOMER CARE, and their action got the truck fixed....

Fast forward 2 years to now.... and I'm now getting a P1C54...... see the following....

So do we think the ECM is now missing the rear (removed) Nox sensor.... or do we assume that the software is correct and the ECM is no missing the information from the front Nox sensor.....

Your thoughts....

P1C54-SCR NOx CATALYST MISSING

Theory of Operation

The after treatment system is equipped with two Nox Sensors and modules. The upstream NOx Sensor 1/1 is located on the Turbocharger elbow downpipe and is permanently connected to a corresponding Nox Sensor Module mounted to the hot side of the engine block. The downstream NOx Sensor 1/2 is located at the outlet of the SCR Catalyst and is permanently connected to a corresponding Nox Sensor Module which is mounted on the right frame rail. The NOx Sensors and NOx Sensor Modules are calibrated to each other and must be replaced as an assembly. The two NOx Sensor and Module asemblies are not interchangeable. The NOx Sensor Modules are smart devices and communicate with the Powertrain Control Module (PCM) over the J1939 Data Link. The NOx Sensor Modules perform their own internal diagnostics and report malfunctions back to the PCM. The NOx Sensors are used to monitor the efficiency of the SCR Catalyst and dosing system. The PCM will illuminate the MIL lamp immediately after the monitor runs and fails. The PCM will turn off the MIL Lamp immediately after the monitor runs and passes.

When Monitored: NOx Sensor data is gathered over varying engine speeds and loads. When enough data has been gathered, the monitor will run, make a pass/fail decision, and begin to gather data again.
Set Condition: The PCM determines that the NOx conversion across the SCR Catalyst is below expectations.

 

[jelag]

So this code self cleared itself.... at least 2 times since the above post... and now I've noticed that when I hit the same ridge in the road, in the same location as I travel home.... the check engine light pops on and this code re-appears...

I assume that under the truck in one of the connectors, it either doesn't make a good connection or there's dirt in the connector.... who knows, maybe its a wire touching the exhaust....

I'm wondering if one of you can confirm this is the connection to the front NOX senor that's in front of the SCR? I was thinking of the next time I have the truck open for service I should open those connections and clean them and apply some dielectric grease....

Any thoughts along this line would be helpful.... your thoughts...