P0148 is a trouble code indicating a possible problem with fuel delivery to the engine. For example, Ford’s criteria is that at least one bank is lean at wide open throttle.
The code is commonly found on diesel-powered vehicles but can also be found on some GDI gasoline powered vehicles. Find out more about this code’s definition, causes, and symptoms with this brief guide.
What Does the P0148 Code Mean?
Diagnostic trouble code (DTC) P0148 stands for “Fuel Delivery Error.” This trouble code is stored when the powertrain control module (PCM) has detected that the actual fuel pressure and desired fuel pressure do not match.
If the low pressure fuel system can’t deliver the proper amount of fuel to the high pressure fuel pump or if the high pressure fuel pump is worn or beginning to fail, the target pressure in the rail cannot be met under heavy loads.
This code may also set if the PCM determines that the input signal from the fuel pressure sensor does not correlate with the specified range.
Common rail systems, whether gasoline direct injection or diesel common rail, have a fuel rail pressure sensor as a feedback input, and the ECM/PCM uses a solenoid in the high pressure pump to drive the fuel pressure to the desired target. If the low pressure pump in the fuel tank isn’t performing up to par, the fuel filter is clogged, or there is a problem with one of the fuel pump modules (for example, Ford Mustangs have two), then code P0148 can be set.
A typical common-rail diesel engine uses an engine-mounted high-pressure injection pump, paired to a low-pressure pump in the tank, that creates the force needed for direct fuel injection. Meanwhile, a fuel control actuator (controlled by either the PCM or a fuel injection controller) regulates fuel pressure to the high-pressure fuel pump.
The PCM uses a fuel pressure sensor, which is usually located near the fuel control actuator, to monitor the fuel pressure while the engine is running. This sensor is also used to determine the amount of fuel going to the injectors.
If the actual fuel pressure is not equal to the commanded fuel pressure, the PCM sets P0148.
Note: The definition of code P0148 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
What Are the Possible Causes of the P0148 Code?
In vehicles equipped with on-board diagnostics, a diagnostic trouble code is set when the PCM detects a potential issue with its performance. Trouble codes can only indicate the location and nature of the problem, not its root cause. It’s up to the owner of the vehicle or the professional mechanic to determine the origin of the error.
Below are just some of the possible reasons why the P0148 code sets:
- Fuel system leak
- Defective fuel pressure sensor
- Defective fuel pump
- Faulty fuel control actuator
- Open, high resistance, or shorted high-pressure fuel supply system wiring and/or connectors
- MAF sensor concern on GDI
- PCM malfunction
- PCM programming error
- Severely restricted fuel filter
- Restricted fuel line
- Air in the fuel system
- Damaged fuel injector/s
What are the Common Symptoms of the P0148 Code?
When the vehicle’s computer stores a diagnostic trouble code, it may also illuminate the appropriate warning lights. For many trouble codes, an active malfunction indicator lamp (MIL) may be the only indicator of an existing issue. However, for other trouble codes, additional signs may be spotted. Listed below are some of the most common symptoms of the P0148 code:
- Malfunction indicator lamp (MIL) or check engine light on
- Increased fuel consumption
- Decreased engine performance
- Excessive exhaust smoke
- Strong diesel fuel odor
- Other fuel and engine drivability codes may also be stored
- Vehicle stalls or refuses to start
How to Diagnose the P0148 Code
Trouble code diagnosis is a time-consuming task that requires technical know-how and, sometimes, even specialized equipment and tools.
However, if you want to understand the P0148 code better, there are a lot of reliable sources you can use as reference. The best resource out there are vehicle-specific repair manuals and databases because they contain detailed repair information as well as helpful illustrations.
How to Fix the P0148 Code
When dealing with the P0148 code, you may want to go to an auto shop to have the issue fixed, especially if you’re not familiar with diesel engine-related problems. This is to avoid property damage and personal injury.
Remember that since trouble codes have multiple possible triggers, narrowing down the root cause of the problem may take some time. Also, terminology, diagnosis, and repair procedures may vary according to the vehicle manufacturer. For example, the setting conditions and possible causes of the P0148 on a Dodge is different from that of a P0148 on a Ford.
Common repair solutions for the P0148 code include fuel injector replacement and diesel injection pump replacement. However, these fixes do not apply to all cases, so thorough diagnosis is still recommended.
Other Notes About P0148
Fuel delivery issues may lead to diminished engine performance and/or potential engine damage. As such, the P0148 code should be addressed immediately, especially if you notice a strong fuel smell.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.