P0190 Code Fix: Fuel Pressure Sensor – Circuit Malfunction
What does the P0190 code mean?
The P0190 code is triggered when the engine control unit is getting a faulty signal from the fuel rail pressure sensor. It is a generic OBD2 code which means it applies to all makes and models from around the year 2000. It applies to both diesel, gas and other fuel types on the market.
The P0190 code is mainly an electric fault to the fuel pressure sensor for the most car models, but in some models, it can trigger the P0190 code if there is a faulty fuel pressure also. You should always start with checking your fuel pressure with a Manual Fuel Pressure Tester.
The engine control unit has a range of the signal of the fuel pressure sensor at given RPM/Boost pressure etc. If the signal from the fuel pressure sensor is falling outside of the calculated signal – The p0190 code will be triggered and stored.
The most common symptom of the P0190 code is just a check engine light ON and you will not have any other symptoms if it is a sensor problem. Because of this trouble code could both mean a sensor problem and a fuel pressure problem, you could also have other symptoms. If you have a sensor problem, the engine control unit will use the default values for the sensor and you may only experience a check engine light.
- Check Engine Light / Service Engine soon Ligh
- The engine will not start
- Hard starting condition/Long cranking time
- The engine makes sudden stops
- Lack of Power
- Limp home mode
- Rough Idle
The most common cause is a failed fuel pressure sensor or faulty wirings to it, but as I mentioned before it can also be a fuel pressure problem depending on what car you have. You should always check your fuel pressure to diagnose this issue.
- Damaged fuel pressure sensor (Most common)
- Faulty wirings to fuel pressure sensor
- Corrosion/bad connection in the fuel pressure sensor connector plug
- Low fuel level
- Bad fuel pump relay
- Bad fuel pump
- Faulty fuel pump wirings
- Clogged fuel filter
- Faulty Fuel pressure regulator
- Faulty Vacuum hose to the fuel pressure regulator
- Faulty engine control unit (Rare)
- Replace fuel pressure sensor
- Clean the connector plug to the fuel pressure sensor
- Repair faulty wirings
- Fill tank level
- Check your fuel pump pressure
- Check fuel pump
- Replace fuel pump relay
- Replace Fuel filter (If low fuel pressure)
- Fix Vacuum leaks (If low fuel pressure)
- Replace Fuel pressure regulator (If low fuel pressure)
- Replace Engine control unit (Rare)
How to diagnose the P0190 code
This is a guide to how a professional automotive technician would diagnose this issue. You may need some car electrician skills and the required tools. I’m sure you can get some good information from it even if you have low knowledge about car electrician. You should always connect a Car battery charger when you are doing any troubleshooting with your vehicle. Low voltage can trigger other unrelated trouble codes that will confuse your troubleshooting. Low voltage can also cause damage to your car’s electronics in the worst case. This guide may differ a bit from different car models. This guide is mainly for petrol engines because some diesel engines use very high pressure and may require special tools to check the fuel pressure
Connect a car battery charger
Start with connecting a car battery charger to your car. Make sure that it is charging your car as it should. I would recommend a car battery charger over 4 amperes, as it may drain out your battery if you are having the ignition ON.
Connect your OBD2 scanner
Connect your OBD2 scanner to your vehicle. Verify the P0190 code. Erase the code and recycle the ignition and start the car(If possible) to see if it is coming back directly. Go into Live data and check the value of the fuel pressure sensor. If the car is not starting and you get a 0bar fuel pressure value, there is most likely a fuel pressure fault.
Locate your fuel pressure sensor
Locate the fuel pressure sensor. Once you have located it you should inspect the connector plug for any corrosion or other damages. Check the wirings if possible. You should now measure the wires with a Digital multimeter. Fuel pressure sensors differ a lot depending on the car model and you should find the right wiring diagram before doing this. But usually, there is one 5 volt power wire, one ground wire and one signal wire. You can check if you get 5 volts and ground from the engine control unit while the ignition is on. If you do not get it, check the wires.
If you find any wiring diagram for your fuel pressure sensor you can measure the resistance on the pins to see if there is a short or open circuit in the sensor.
Check the fuel pressure (Petrol)
Checking the fuel pressure is the most important task for this troubleshooting. To check the fuel pressure you have to get a Manual Fuel Pressure Tester with the right adapters to fit your fuel rail / Fuel Hose. Let a friend checking the fuel pressure while you are cycling the ignition. The fuel pump should normally prime around 10 seconds after you have turned on the ignition. Start your car to check your fuel pressure
If you get no fuel pressure
If you do not get any fuel pressure, you should diagnose the following parts:
- Fuel pump
- Fuel pump relay
- Fuel pump wirings
- Fuel filter
- Fuel pressure regulator
- Internal leak inside fuel tank on fuel pressure hose
Recommended Tools to Fix P0190
- Read the Trouble code memory: FOXWELL NT301 Scan Tool. For advanced troubleshooting, you may need a more advanced code scanner.
- Car Battery charger: NOCO Genius G3500 6V/12V Smart Battery Charger
- To measure the wires/fuel pressure sensor: Digital multimeter
- Checking your fuel pressure: Manual Fuel Pressure Tester
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