Fault code P0148 is called “Fuel Delivery Error” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P0148
Stored code P0148 means that the control module (PCM) has detected a problem in the fuel system. This error is used exclusively on vehicles with diesel engines.
The fault is set when the Powertrain Control Module (PCM) detects that the actual and desired fuel pressures do not match. This code can also be set if the PCM detects that the input signal from the fuel pressure sensor does not match the desired range.
Most diesel engines have a high pressure pump connected to the low pressure pump in the tank. This creates the force required for direct fuel injection.
The PCM controller controls the fuel supply by adjusting the pressure by feeding it to the high pressure fuel pump.
The PCM uses a fuel pressure sensor, usually located next to the supply control actuator, to control fuel pressure while the engine is running. This sensor is also used to determine the amount of fuel flowing to the injectors.
Error code P0148 is set when the control module (PCM) detects that the fuel rail pressure sensor, is not working correctly. That is, the actual fuel pressure differs from the set pressure.
Symptoms of vehicle malfunctions
The main signal that an error P0148 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
- Other related fault codes may also be present.
- The engine stalls or starts poorly.
- There is a strong odor of diesel fuel
- Decreased power output of the engine.
- Increased fuel consumption.
The severity of error P0148 is high, the cause should be eliminated as soon as possible. The malfunction can lead to a loss of performance, as well as damage to the engine.
Factors that can cause this error code
The error code P0148 can mean that one or more of the following problems have occurred:
- Leak in the high-pressure fuel system.
- Damaged fuel line.
- Faulty fuel pressure sensor.
- Faulty fuel control actuator.
- Fuel pump malfunction.
- Damaged connector or wiring problem.
- Excessive resistance in electrical circuit.
- Problem with PCM power relay.
- Sometimes faulty PCM module is the cause.
How to fix or reset OBD-2 code P0148
Some suggested steps for troubleshooting and fix the error code P0148:
- Read all stored data and error codes with an OBD-II scan tool.
- Clear the error codes from the computer memory.
- Test-drive the vehicle to find out if error P0148 appears again.
- Check the high-pressure fuel system for leaks.
- Visually inspect the connector and electrical wires for damage. If present, repair the damaged areas.
- Check the resistance to make sure it is within tolerance.
- Test the fuel pressure sensor.
- Test the power relay and PCM module.
Diagnose and repair of problems
Locate the fuel pressure sensor, once found, visually inspect the connector and wiring. Look for scuffs, exposed wires, burn marks, or melted plastic. Disconnect the connectors and carefully inspect the terminals inside. Check them for rust and other damage.
Remove diagnostic trouble code P0148 from the memory, test drive it and see if it comes back again. If it is gone, the problem was in the wiring or connection.
If the fault code returns, we will need to test the sensor and associated circuits. In addition, we need to test the high pressure system for leaks.
Checking for leaks
If a strong diesel odor is present, there is a high probability that pressure loss due to a leak is the cause of the problem. If a fuel leak is detected, the fuel filters and other components that have been recently replaced should be carefully inspected before proceeding.
If there are no leaks and the fault code has been reset, use a fuel pressure gauge to check the fuel pressure.
When the actual fuel pressure does not meet the manufacturer’s specifications, there are several reasons. These include a faulty fuel pump, a clogged fuel filter, or a bad fuel pump relay.
You can check the fuel pump operation by using a multimeter to check the voltage at the connector when voltage is applied. If voltage is present but the fuel pump does not work, it is likely faulty. If there is no voltage at the fuel pump connector, there is most likely a faulty fuel pump, relay, or wiring problem.
Checking the fuel pressure sensor
The fuel pressure sensor is usually wired with a 5 volt reference signal and ground. The variable resistance fuel pressure sensor closes the circuit and provides a pulse signal to the PCM.
Check the reference voltage and ground at the fuel pressure sensor connector with a multimeter. If there is no reference voltage on the sensor connector, check the parallel circuits on the PCM connector.
If no reference voltage is detected on the PCM connector, the problem may be a faulty PCM or a PCM programming error. But consider a faulty PCM as the main cause of error P0148 only as a last resort.
On which vehicles does this problem occur most frequently
Fault code P0148 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Audi
- Chevrolet
- Chrysler (PT Cruiser)
- Citroen
- Dodge (RAM)
- Fiat (Ducato)
- Ford (Explorer, Mondeo, Mustang, Transit)
- GMC
- Mazda (5)
- Mitsubishi (Fuso)
- Peugeot (Boxer)
- Ssangyong (Kyron)
- Toyota (Tundra)
- Volkswagen
- GAZelle (Next)
Fault code P0148 can sometimes be found with other errors. The most common are the following: P0147, P0149, P0168, P0169, P0170, P0173.
