P2201

[Larry Willard]

Just got a check engine light, code P2201 for a Nox sensor. Should I just clear the code and see if it comes back.Is it safe to drive another 300-400 miles or not?

 

[JLandry]

Larry,

If you only got that one DTC, then I'd just clear it and watch for a return. If it does come back, definitely take it in.

P2201 is triggered by a failure of a routine N0x sensor circuit check. It doesn't necessary mean the sensor has failed.

Safe travels,

John

 

[Larry Willard]

Thanks John, that was what I was thinking, and what I have always done in the past. The check engine light tripped about 2 minutes after start-up.

Larry

 

[Bob4x4]

The aftertreatment 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 Malfunction Indicator Lamp (MIL) after the diagnostic runs and fails in two consecutive drive cycles. The PCM will turn off the MIL immediately after the monitor runs and passes.

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• When Monitored:This diagnostic monitor consists of two separate checks. The first check occurs when the engine exhaust temperature at NOx Sensor 1/1 is above 150°C (302°F), and the engine is in a decel condition with zero fueling. The second check occurs when the engine exhaust temperature at NOx Sensor 1/1 is above 150°C (302°F), and the calculated NOx value is changing.
  
• Set Condition:The Powertrain Control Module detects that the NOx Sensor 1/1 reading is not reading zero during decel condition with zero fueling for two consecutive trips or the PCM has detected that the NOx Sensor 1/1 reading is not changing with engine conditions for two consecutive trips.
  
• 
  

 

[Larry Willard]

Thanks Bob, if I understand correctly you are saying I should have just taken it in and not cleared the codes? So far I have had a couple warm starts with no light, but no cold starts yet.
Larry

 

[sag2]

Larry, first off there is a flash from November 2015 that addresses a possible false P2201 setting. The TSB is 18-057-15 Rev. A. If your truck has not been flashed since the TSB release that might be a good place to start. Otherwise you can force the monitor to run by doing the following. First, clear the code. Then follow the procedure below. Don't be too concerned about exhaust temp. Just drive it for a mile or two before doing the decels. After doing the procedure and the code does not reset the problem is not there now. If it resets it is time to stop in at the dealer. It isn't going to leave you stranded.

1.	Start the engine, monitor Exhaust Gas Temperature Sensor 4 until it reaches 150°C (302°F).

2.	Drive the vehicle at 50 MPH, ensure that it is not in DPF Regeneration mode.

3.	Perform a zero fueling event (decel condition for 10 seconds, with foot off of accelerator pedal).

4.	Repeat this condition three to five times.

5.	With the scan tool check active DTCs.

 

[Larry Willard]

Thanks Stan. I have now towed 100 miles since I cleared the code with it not resetting.....yet. The last time I was at the dealer that they did any updates was in November last year, so not sure if it was one on the ones they did. Next time I drive I will be sure to do your monitor runs.

Larry

 

[Larry Willard]

I have now towed 100 miles, drove back with out trailer and have run 5 or 6 short trips of about 5 miles or less, did the test Stan described with no return of any codes.

Larry