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Home >> Chrysler >> 2011 >> 300 C, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 94 (6.7L Diesel - DTCS P2000 To U1601 - 2500 & 3500) >> Diagnosis and Testing >> P21B2-Excessive Time To Enter Closed Loop NOX Absorber Control >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2011 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes 
MASS AIR FLOW (MAF) SENSOR VALUE NOT LEARNED
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

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to  PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE - 6.7L  .