P0193 is a generic OBD-II code that can occur in the Subaru Liberty. It indicates that your Liberty’s fuel rail pressure sensor is sending a signal to the PCM that is above its normal operating range (in terms of voltage value).
While P0193 is a generic code (it has the same meaning for any vehicle made for the 1996 model year and up), it can have different repair steps depending on what type of engine your Subaru has and the model year.
With P0193 there can only be two things going on with your Liberty:
- The fuel pressure reading is correct and abnormally high (likely a fuel pressure regulation issue).
- The fuel pressure reading is incorrect (bad fuel pressure sensor, or wiring issue).
P0193 Symptoms: Subaru Liberty
With P0193, there will likely be some observable symptoms.
Stalling
With too much fuel getting to your Liberty’s fuel injectors or the PCM, the engine may stall out or hesitate in certain situations. There may also be a noticeable lack of power.
Air/Fuel Mixture Issues
Without a reliable reading from the fuel pressure sensor, your vehicle may end up with the wrong air/fuel mixture. If it runs too rich, you may get black smoke and P0172.
Unreliable Idle
P0193 can be caused when the fuel pressure regulator is bad. If the fuel pressure at the injectors is inconsistent, it’ll be really hard for your vehicle to maintain a steady idle speed. This can lead to the engine dying when coming to a stop as well.
Poor Fuel Mileage
Fuel mileage can suffer when the air/fuel mixture isn’t correct. You may also notice the stench of gas.
P0193 Causes: Subaru Liberty
Here are the most common issues that cause P0193 to be thrown in the Subaru Liberty:
Fuel Pressure Sensor
The fuel pressure sensor is responsible for telling your Liberty’s ECM/PCM what the actual fuel pressure is. If it goes bad (or if the fuel pressure really is out of the normal range) P0193 can and will appear.
A bad fuel pressure sensor can force the vehicle to overwork the fuel pump, thinking that it’s constantly starving for fuel when it is not.
Wiring
Wiring issues can cause P0193 to be thrown. Take a look at the wiring harness around your Liberty’s fuel pressure sensor. Does it look broken or damaged? Is the connection to the sensor solid? If it looks bad, it may need to be replaced.
Fuel Pressure Regulator
The fuel pressure regulator is responsible for making sure that the amount of fuel pressure that reaches the fuel rail is at a constant level (which will be less than pushed by the fuel pump). If your Liberty’s fuel pressure regulator goes bad, it can restrict the flow of fuel to the point that P0193 can be thrown.
P0193 Diagnosis
A good scanner can help you look at the conditions that were present when the code was set. You can also use it to check the fuel pressure reading as you drive.
You’ll need to manually check your Liberty’s fuel pressure if the reading seems off.
If the manual fuel pressure reading is normal, then you know that you’ve got an issue with the fuel pressure sensor (or the wiring going to and from it).
If the fuel pressure reading is high, it’s likely the fuel pressure regulator causing P0193.
Conclusion
P0193 in the Subaru Liberty can be a difficult code to track down, but should not be ignored. Doing so very well could leave your vehicle stranded. If there is anything that you would like to add, please leave a comment below. Good luck.