P20F7 Reductant Injection Valve Stuck Open Bank 2 Unit 1
OBD-II Trouble Code Technical Description
Reductant Injection Valve Stuck Open Bank 2 Unit 1
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Ford, Mercedes Benz, Sprinter, Smart, Ram, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
A stored code P20F7 means that the powertrain control module (PCM) has detected a stuck open reductant injection valve for engine bank 2 and selective catalyst reduction (SCR) system 1. Bank two refers to the bank of the engine that doesn't contain the #1 cylinder.
The catalyst system is responsible for reduction of (basically) all exhaust emissions although certain applications are also equipped with a NOx trap.
Exhaust gas recirculation (EGR) systems go another step further in the reduction of NOx. Nevertheless, today's larger and more powerful diesel engines cannot meet strict federal (U.S.) emission standards with the EGR, diesel particulate filter/catalytic converter, and NOx trap alone. It was for this reason that selective catalytic reduction (SCR) systems were invented.
SCR systems inject a reductant compound or a diesel exhaust fluid (DEF) into the exhaust in front of the diesel particulate filter, NOx trap, and/or the catalytic converter via the reductant injection valve (solenoid). The precisely timed DEF injection elevates the temperature of the filtration element and allows it to perform more efficiently. It enhances filtration element longevity and allows fewer harmful exhaust emissions to be released into the atmosphere.
The entire SCR system is monitored and controlled by either the PCM or a stand-alone controller (which interacts with the PCM). Either way, the controller monitors the O2, NOx, and exhaust temperature sensors (as well as other inputs) to determine the appropriate time for DEF (reductant) injection. Precise DEF injection is necessary to maintain exhaust temperature within acceptable parameters and optimize pollutant filtration.
Reductant heaters are used to prevent diesel exhaust fluid from freezing during extreme temperatures. These heaters are typically located in the DEF reservoir and/or the reductant injector supply hose/s.
What is the severity of this DTC?
A stored code P20F7 should be considered severe and addressed as quickly as possible. The SCR system could be disabled because of it. Catalyst damage could result if the conditions which contributed to the code being stored are not rectified in a timely manner.
What are some of the symptoms of the code?
Symptoms of a P20F7 trouble code may include:
Diminished engine performance Excessive black smoke from vehicle exhaust Reduction in fuel efficiency Other SCR related codesWhat are some of the common causes of the code?
Causes for this code may include:
Bad reductant injection valve Open or shorted circuits in the reductant injection valve control Insufficient DEF in the reservoir Bad SCR controller/PCM or programming errorWhat are some P20F7 troubleshooting steps?
You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle specific diagnostic information to diagnose a code P20F7.
If you can find a technical service bulletin (TSB) that matches the vehicle year, make, and model; as well as the engine size, code/s stored, and symptoms exhibited, it could yield helpful diagnostic information.
You will want to begin your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burnt or damaged wiring and or connectors should be repaired or replaced before proceeding.
Proceed by hooking th
Read: 26
