P0193 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.

Definition

P0193-Fuel Rail Pressure Sensor Circuit High Input

Meaning

Your vehicle’s power control module (PCM)  is not reading within manufacturer specifications. In simpler terms, due to an unknown cause your car isn’t producing sufficient power to run the engine and move the car. This loss of power triggers a P0193 trouble code in the PCM, and the Check Engine Light will come on.

Causes

As with most power loss issues on a car, there are just a few probable causes that can trigger a P0193. Here are the most common causes to get your started on a diagnosis:

  • Low fuel or an empty fuel tank (the car does need fuel to run)
  • Wiring that is exposed, broken, shorted, or corroded (the second thing you should check after the fuel level)
  • Connectors that are corroded (check this after wiring)
  • Fuel filter that is clogged (if you’ve never run a fuel system cleaner through your car, this is a likely culprit)
  • Defective fuel pump relay (the fuel pump isn’t getting the signal from the PCM to pump fuel)
  • Bad fuel rail sensor (sensors do go bad over time and need to be replaced)
  • Defective fuel pump (the pump itself is broken and does not move fuel through the system anymore)

Symptoms

Knowing what to expect from your car can help you narrow down the diagnosis of the root problem for a P0193 trouble code. Here’s a short list of probable symptoms you may experience:

  • The Check Engine light will illuminate
  • The car will not start up or turn over
  • The car will take longer than normal to start (it may take a few tries to get it started)

The car will hesitate during acceleration (when you press the accelerator, the engine will not respond right away)

Diagnosis

Every shop is different, and every technician has their own way of doing things. That being said, this is how we recommend you diagnose a P0193 trouble code on a vehicle to find and fix the problem the first time.

  • The first thing every technician should do is inspect all wiring and connectors for melting, breaks or worn insulation and corrosion. In many cases, fixing or replacing damaged wires or connectors corrects a multitude of problems for a vehicle that hasn’t been functioning properly or that has a Check Engine light on.
  • Next, your tech will connect an OBD-II scanner to retrieve freeze-frame data and trouble codes stored by the power control module.
  • After pulling trouble codes, the tech will take your vehicle for a test drive to see if they experience the same symptoms you described when you dropped your vehicle off for service. When they return from the test drive, they will clear the codes and verify if the P0193 reoccurs.
  • If P0193 does not pop up immediately on the second scan, it’s possible the cause of the code is an intermittent issue. You may need to take the “wait-and-see approach” and determine if the problem gets worse in order for them to find the root cause of the trouble code.
  • For non-starting cars, there is always the possibility that there is no fuel in the fuel tank regardless of what the fuel gauge is currently reading.. Most technicians will use a fuel pressure gauge to check the fuel pressure. If it reads low, the car has little to no fuel. If that’s not the issue, the next step is to start checking out the fuel pump..
  • The first step of checking the fuel pump is simply to listen to it while the vehicle is running. If the car won’t start but the fuel pump turns on, its likely an electrical problem.
  • A non-starting car and a silent fuel pump means a tech will attempt starting the car while another person taps on the bottom of the fuel tank. If the car starts, this means the fuel pump needs to be replaced.
  • Finally, if the car won’t start, the technician will use a multimeter to check the battery voltage at the fuel pump connector. No battery voltage at that connection means they move on to check the fuse circuit, pump relay circuit, and PCM for faults or shorts.
  • If all circuit connections to the battery and PCM come up clean, your technician will inspect the fuel rail pressure sensor itself. Using a multimeter once more, the tech checks the reference voltage of the fuel rail pressure sensor while the car is running. The voltage reading should be 5-volts. Should you pull five volts on the sensor, the next part of the system that needs checking is the ground wire.
  • Good to go on the sensor circuit and ground? Your tech will switch the multimeter over to ohms. And verify the sensor’s resistance readings do not vary from manufacturer’s specifications. An out of range resistance reading means the sensor is bad and needs to be replaced.
  • Last but not least, if everything is functioning normally and testing normally, but the problem remains, it’s possible the PCM is defective. That would be an expensive replacement and reprogramming process, so make sure you check absolutely everything else before deciding that’s the cause of your problem.

Common mistakes

Even the most experienced automotive mechanics and technicians make mistakes, and it’s important to be aware of what details often get overlooked when diagnosing the root cause of P0193.

First and foremost, make sure there is gas in the tank. An empty gas tank is going to pull that trouble code as surely as a faulty fuel pump. Filling up the tank is a lot cheaper than replacing parts in your fuel system.

Second, always check the wiring and connectors to the fuel pump and PCM for damage. Overlooking faulty wiring or bad connectors can make a potentially easy fix into a drawn out and expensive one if the only problem is some frayed wiring or a corroded connector.

How serious is this?

P0193 is one of those codes where you stop whatever else you are doing and take it straight to the shop. You may lose the ability to start the car and get it to the shop, or you may suffer a loss of power when merging on the highway or attempting to pull out across a busy intersection. If you see the check engine light and notice a loss of power, don’t wait! Take your vehicle in right away.

Repairs For Fixing a P0193

  • Add fuel to the fuel tank (hopefully that’s the only problem)
  • Repair broken or shorted wires (often the most likely culprit)
  • Repair corrosion of the wiring and/or connectors (second most likely culprit)
  • Replace clogged fuel filter (an easy fix that's relatively inexpensive)
  • Replace fuel pump relay (another inexpensive fix)
  • Replace fuel pump fuse (again, simple and inexpensive)
  • Replace fuel pump (moderately expensive and somewhat time-consuming)
  • Replace the fuel rail pressure sensor (cost varies by vehicle, and sometimes it doesn’t fix the problem because the root cause was actually something else in the fuel system)

Related codes

None listed.

Conclusion

If you notice trouble starting your car, hesitation on acceleration, or a loss in power even when you have the pedal to the metal, take your vehicle into the shop and see if it pulls a P0193. It's usually a simple fix that won’t cost a fortune, and it’s critical to keeping your car running and not leaving you stranded by the side of the road.