Technical Description of OBD-II Trouble Code
This code refers to Fuel Pressure Regulator 2 – Forced Engine Shutdown.
What is the meaning of P228B?
P228B is a generic powertrain code that applies to many OBD-II vehicles (1996-newer), including Volkswagen, GMC, Chevrolet, Cadillac, Ford, BMW, and others. The exact repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
In my personal experience, a P228B has only been observed in diesel powered vehicles. It indicates that the powertrain control module (PCM) has detected an excessive degree of fuel pressure in the electronic fuel pressure regulator, which is severe enough to warrant engine shutdown.
The regulator in question is designated with a 2. Systems that use multiple electronic fuel pressure regulators often use a numerical designation. The 2 may also refer to a certain bank of the engine. Please refer to the manufacturer’s specifications for the specific vehicle. It is important to note that high pressure diesel fuel injection systems should only be serviced by qualified personnel.
The PCM (or some type of integrated diesel controller) monitors and controls the electronic fuel pressure regulator. It adjusts the pressure regulator voltage constantly based on input data from the fuel pressure sensor, which is located in the fuel injector rail. The PCM uses battery voltage and ground signals to control a servo motor in the fuel pressure regulator. This servo motor actuates a valve that ensures the desired level of fuel pressure is achieved for any given situation.
When the voltage is increased at the electronic fuel pressure regulator servo motor, a valve is opened and fuel pressure is increased. Decreased voltage at the servo causes the valve to close and fuel pressure is decreased. The fuel pressure regulator and fuel pressure sensor are typically integrated into a single housing with one electrical connector, but they may also be separate components.
If the PCM detects that the fuel pressure regulator 2 control circuit voltage is not within a certain parameter as computed by the PCM, a P228B code will be stored and a malfunction indicator lamp (MIL) may be illuminated. Forced engine shutdown is likely to occur as well.
A typical fuel pressure regulator:
What is the severity of this DTC?
A code P228B should be categorized as severe because insufficient or excessive fuel pressure can cause internal engine and catalytic converter damage and lead to various drivability issues.
What are some of the symptoms of the code?
Symptoms of a P228B trouble code may include:
What are some of the common causes of the code?
Causes for this code may include:
What are some P228B troubleshooting steps?
In order to accurately diagnose a code P228B, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information.
It may save time to search for technical service bulletins (TSB) that match the stored code, vehicle information (year, make, model, and engine), and exhibited symptoms. This information can usually be found in your vehicle information source. If the right TSB is found, it may provide a quick solution to the diagnosis.
After connecting the scanner to the vehicle diagnostic port and retrieving all stored codes and freeze frame data, write down the information in case the code is intermittent. Then, clear the codes and test drive the vehicle until one of two things happens: the code is restored or the PCM enters readiness mode.
If the PCM enters readiness mode at this point, the code may be more difficult to diagnose because it is intermittent. The condition that caused the P228B to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, continue with the diagnosis.
You can obtain connector face views, connector pinout charts, component locator charts, wiring diagrams, and diagnostic flow charts for the specific code and vehicle using your source of vehicle information.
Perform a visual inspection of the related wiring and connectors. Repair or replace any wiring that is cut, burned, or damaged.
Use the DVOM to test the voltage and ground circuits at the electronic fuel regulator (2) and fuel pressure sensor/s. If no voltage is detected, check the system fuses and replace any blown or defective fuses as necessary.
If voltage is detected, test the corresponding circuit at the PCM connector. If no voltage is detected there, suspect an open circuit between the sensor in question and the PCM. If voltage is discovered there, suspect a defective PCM or PCM programming error.
Test the fuel pressure regulator and fuel pressure sensor with the DVOM. If either of them does not comply with the manufacturer’s specifications, consider it defective.
If the fuel regulator (2) and sensor/s appear to be functioning properly, use a manual fuel pressure gauge to test the actual fuel pressure at the rail in an effort to replicate the failure condition.
