The OBD2 code P0192 is defined as “Fuel Rail Pressure Sensor Circuit Low,” indicating that the signal received by the engine control module (ECM) from the fuel rail pressure sensor is below the expected range.
This sensor plays a critical role in monitoring the fuel pressure within the rail to ensure optimal engine performance and efficiency. Let’s break down this diagnostic trouble code through the lens of the service cases from Dodge, Mercedes, and Chevrolet vehicles.
P0192 quick overview
| Meaning | P0192: Fuel Rail Pressure Sensor Circuit Low |
| Is it serious? | Yes, this code is serious because it can lead to poor engine performance, including rough idling, poor acceleration, and potentially stalling, which could compromise vehicle safety. |
| Possible causes | – Faulty fuel rail pressure sensor – Wiring or connection issues (corrosion, damage, or loose connections) – Low fuel pressure – Problems with the powertrain control module (PCM) |
| How to diagnose? | Verify the fuel pressure to ensure it’s within the manufacturer’s specified range. Inspect the fuel rail pressure sensor and its connections for any signs of damage or corrosion. Check the wiring for shorts, opens, or poor connections that could affect sensor readings. Consider updating or flashing the PCM if all other components are functioning properly. |
P0192 Meaning
When your vehicle’s computer flags the P0192 code, it’s signaling a hiccup with the sensor that gauges how much pressure is in the fuel rail, the pipe that delivers fuel to the injectors.
Think of this sensor as a fuel pressure “thermometer” for your car’s engine. If the “thermometer” reads too low, it could mean there’s a problem with the sensor itself, the wiring connected to it, or even the fuel pressure, which is crucial for your engine to run smoothly. Addressing this issue promptly is important to maintain your vehicle’s performance and avoid potential engine damage.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
How to fix P0192 – learn from mechanics
I looked into P0192 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Dodge
Vehicle Information 2005 Dodge Ram 2500 Laramie 5.9L
Issue + Repair History
- Truck came in with a history of turbo failure and subsequent engine damage.
- Engine replaced with a Jasper engine, all 6 injectors checked, and the injector pump inspected.
- Persistent code P0192 (low volts to fuel sensor) detected, unable to clear.
- Rough idle observed, slow throttle response, and engine sounds like it’s pinging at idle.
Other OBD2 Codes + Test Results
- P0192 – Low volts to fuel sensor.
Mechanic Suggestions
- Check the fuel control actuator to ensure it’s properly plugged in.
- Verify fuel pressure to the injection pump as low fuel pressure feed could be causing issues.
- Consider flashing or updating the PCM to potentially resolve code issues.
- Double-check the grounding on the circuit related to the fuel sensor.
Final Fix
- Customer took the truck to a dealer who confirmed a faulty fuel pressure sensor. Replacing the sensor resolved the issue, and the truck ran fine afterward.
Case #2: Mercedes
Vehicle Information 2005 Mercedes-Benz E320 CDI 3.2L
Issue + Repair History
- Check engine light on with codes P0192 (fuel rail pressure sensor voltage too low) and P0652 (sensor B circuit supply voltage too low).
- Idle fluctuations and poor acceleration experienced.
- Fuel filter replaced initially, but P0192 code persisted.
- Testing revealed no 5v reference at the sensor with it plugged in, but voltage returned with the sensor unplugged, setting P0193 (voltage too high).
- Fuel rail pressure sensor replaced, codes cleared, and issues resolved.
Other OBD2 Codes + Test Results
- P0192 – Fuel rail pressure sensor voltage too low.
- P0652 – Sensor B circuit supply voltage too low.
- Fuel rail pressure at idle: 5800 psi.
- Fuel rail pressure at wide-open throttle/load: 16675 psi.
Mechanic Suggestions
- Try replacing the fuel filter first before replacing the fuel rail pressure sensor.
- Ensure the fuel tank and delivery units are clean before sensor replacement, as contamination can affect the sensitive fuel system.
- Check fuel delivery to the high-pressure pump before replacing any other parts, including checking return fuel quantity and flow rate.
Final Fix
- Replacing the fuel rail pressure sensor resolved the issue after the initial replacement of the fuel filter did not.
Case #3: Chevrolet
Vehicle Information 2009 Chevrolet Traverse LS 3.6L
Issue + Repair History
- Check engine light on with code P0192 (fuel rail pressure sensor low voltage).
- Scanner shows 0 pressure and 0 volts for fuel rail pressure sensor.
- New fuel rail pressure sensor installed, but readings remained the same.
- 5-volt reference and good ground confirmed to the sensor.
- Signal wire also showing 5 volts with the sensor unplugged.
- No short to voltage found in signal wire from PCM to sensor.
- Suspected PCM issue due to abnormal signal wire behavior.
Other OBD2 Codes + Test Results
- P0192 – Fuel rail pressure sensor low voltage.
- P0652 – Sensor B circuit supply voltage too low.
- Signal wire voltage with sensor plugged in: 2.46 volts KOEO and 1.45 volts KOER.
- Fuel rail pressure at idle: 0 psi.
- Fuel rail pressure at wide-open throttle/load: 0 psi.
Mechanic Suggestions
- Check signal wire voltage with sensor plugged in and ensure consistency with PCM readings.
- Verify continuity between signal and VREF wires to rule out shorting.
- Consider trying another scanner to confirm scan tool data accuracy.
- Check for any relevant bulletins or programming updates before replacing the PCM.
Final Fix
- The issue was traced to a chewed signal wire between the fuel line pressure sensor and the fuel pump control module.
- Replacing the damaged wire resolved the problem, avoiding unnecessary PCM replacement.
How to diagnose P0192
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Brief Explanation |
|---|---|
| Inspect the fuel rail pressure sensor | Check for physical damage or contamination that could impair its function. |
| Verify fuel pressure | Ensure the fuel system is delivering sufficient pressure for proper engine operation. |
| Check wiring and connectors | Look for damage, corrosion, or loose connections that could affect signal transmission. |
| Update/flash PCM | Update the vehicle’s computer software to ensure it correctly interprets sensor data. |
| Replace fuel rail pressure sensor | If the sensor is faulty, replacing it is often the solution to resolving the P0192 code. |
| Repair damaged wiring | Fix any identified issues with the wiring, especially if damage interrupts the sensor’s signal path. |
These cases illustrate the importance of a thorough diagnostic approach when dealing with the P0192 code. While the symptoms and fixes can vary—ranging from replacing a faulty sensor to repairing damaged wiring—the goal remains the same: to ensure the fuel system is accurately monitored for pressure, safeguarding engine performance. Vehicle owners experiencing similar issues should seek professional assistance to accurately diagnose and resolve the underlying cause of the P0192 code.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko