P2055 Reductant Injection Valve Circuit High Bank 1 Unit 2
OBD-II Trouble Code Technical Description
Reductant Injection Valve Circuit High Bank 1 Unit 2
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 P2055 means that the powertrain control module (PCM) has detected excess voltage in the control circuit for the reductant injection valve for engine bank one and selective catalyst reduction (SCR) system two. Bank 1 refers to the bank of the engine that contains the number one cylinder. Unit 2 indicates that multiple reductant injection or SCR systems are in use.
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.
If the PCM detects excess voltage on the control circuit for the reductant injection valve for engine bank one unit two, a code P2055 will be stored and a malfunction indicator lamp may be illuminated.
What is the severity of this DTC?
A stored code P2055 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 P2055 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 P2055 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 P2055.
If you can find a technical service bulletin (TSB) that matches the vehicle year, make, and model; as well as the engine size, code/
Read: 26
