P21B2 code

[Plum Crazy]

I keep getting a code P21B2 code. It’s a Nox closed loop excessive time description. Has anyone experienced this before? Got it resolved? How?

 

[Topzide]

@Plum Crazy, Don't have an answer for your question but you may want to fill in truck info on signature line. That way we'll be able to see what type truck you have and won't be asking for it in reference to anything you may post. I'm sure someone will have an answer. Great group of people passing on their knowledge!

 

[Plum Crazy]

@Plum Crazy, Don't have an answer for your question but you may want to fill in truck info on signature line. That way we'll be able to see what type truck you have and won't be asking for it in reference to anything you may post. I'm sure someone will have an answer. Great group of people passing on their knowledge!

Done, Thank you

 

[sag2]

These are the possible problems. You need to diagnose it properly to get to the solution.

MASS AIR FLOW (MAF) SENSOR VALUE NOT LEARNED
O2 SENSOR 1/1
EGR VALVE STICKING OR RESTRICTED
THERMOSTAT OUTLET RESTRICTED
EGR CROSSOVER TUBE RESTRICTION
FAULTY EGR COOLER BYPASS CONTROL VALVE
FAULTY EGR AIR FLOW CONTROL VALVE
FOULED EGR COOLER
IMPROPER FUELING
LEAKING OR DAMAGED NOX ABSORBER CATALYST
SMART O2 MODULE

 

[Plum Crazy]

These are the possible problems. You need to diagnose it properly to get to the solution.

MASS AIR FLOW (MAF) SENSOR VALUE NOT LEARNED
O2 SENSOR 1/1
EGR VALVE STICKING OR RESTRICTED
THERMOSTAT OUTLET RESTRICTED
EGR CROSSOVER TUBE RESTRICTION
FAULTY EGR COOLER BYPASS CONTROL VALVE
FAULTY EGR AIR FLOW CONTROL VALVE
FOULED EGR COOLER
IMPROPER FUELING
LEAKING OR DAMAGED NOX ABSORBER CATALYST
SMART O2 MODULE

Thank you for sharing this information. I just cleaned the EGR and cooler. Changed the coolant at the same time. Cross over tube looked fine. I guess it is either the O2 sensor, module, or the NOX absorber.

 

[PRS]

Might be worth logging the commanded vs. actual position of the EGR to see how it's acting. Not saying cleaning doesn't help, but if you can log it, it might become apparent.

 

[Plum Crazy]

Might be worth logging the commanded vs. actual position of the EGR to see how it's acting. Not saying cleaning doesn't help, but if you can log it, it might become apparent.

How do you know what the computer has commanded? How do you determine what position the EGR valve is in?

 

[PRS]

How do you know what the computer has commanded? How do you determine what position the EGR valve is in?

You can use an MX+ and the OBDLink app that goes with it to graph the commanded position vs the actual position on your Iphone or Android device. MX+ can also be used with AlphaOBD for configuration changes and testing. About the same price as an oil & filter and fuel filters change you did yourself.

 

[Topzide]

Side note: AlfaOBD work on Android and Windows OS only. At this point in time, not sure if it will be offered in Apple OS. If you have an Iphone, just get an Android tablet to run AlfaOBD. I have both tablet and phone for AlfaOBD. Like the size on tablet, but always have the phone with me if and when needed. AlfaOBD is worth the price even if you need to purchase a tablet! Great tool for the toolbox!