OBD-II Code P0191 is defined as a Fuel Rail Pressure Sensor “A” Circuit Range/Performance. This code indicates that there are issues with the readings from the fuel rail pressure sensor or its circuit, leading to abnormal fuel pressure conditions.
What Does the P0191 Code Mean?
The Power Train Control Module (PCM) relies on the fuel rail pressure sensor to gauge the fuel pressure that is being delivered to the fuel injectors. This information is critical for the PCM to control the fuel injectors effectively, ensuring the right amount of fuel is injected into the engine for optimal performance and fuel efficiency. When the PCM detects erratic signals from the fuel pressure sensor, it triggers the P0191 code.
What Causes the P0191 Code?
The P0191 code can be triggered by several factors, including:
- Defective Fuel Pressure Sensor
- Faulty Fuel Pressure Sensor Circuit or connector
- Damaged or defective Fuel Pressure Regulator
- Poor connections or chafed wiring
- Defective fuel pump
What Are the Symptoms of the P0191 Code?
When the P0191 code is present, you may experience the following symptoms:
- Illumination of the Check Engine Light
- Higher than normal fuel consumption
- Unusual tailpipe emissions
- Engine hesitation or stalling
- Engine may die or stall at stop signs
- Rich or lean fuel trim codes may be triggered (P0172 or P0171)
- Vehicle may fail emissions tests
- In some cases, there may be no noticeable symptoms
How Serious Is the P0191 Code?
The P0191 code is classified as urgent. Failure to address this issue promptly can lead to severe damage to the vehicle and pose risks to the driver and passengers. It is crucial to diagnose and repair this code as soon as possible to avoid further complications.
How to Diagnose the P0191 Code
To diagnose the P0191 code, follow these steps:
- Gather Freeze Frame Data to analyze the engine’s operating conditions when the code was set.
- Test drive the vehicle using a quality data streaming scan tool and monitor the fuel pressure PID.
- If fuel pressure readings appear abnormal, use a mechanical fuel pressure gauge to check the actual fuel pressure.
- If pressure is normal, inspect the Fuel Rail Pressure Sensor connector and wiring using a labscope.
- If the circuitry is intact and fuel pressure is normal, the sensor is likely at fault.
- If fuel pressure readings are erratic, inspect the fuel delivery system and perform an amperage draw test on the fuel pump.
Common Repairs for the P0191 Code
Common repairs involving the P0191 code may include:
- Replacing the defective Fuel Pressure Sensor
- Repairing or replacing the Fuel Pressure Sensor Circuit or connector
- Replacing a damaged Fuel Pressure Regulator
- Fixing poor connections or chafed wiring
- Replacing a faulty fuel pump
How Much Does It Cost to Fix the P0191 Code?
The cost to fix the P0191 code can vary widely depending on the specific issue, labor rates, and parts required. Typically, you can expect to pay anywhere from $100 to $500 for repairs, depending on the diagnosis and parts needed.
Can I Fix the P0191 Code Myself?
While some aspects of diagnosing the P0191 code can be performed by a knowledgeable DIYer, such as checking connections and replacing sensors, it is recommended to have a professional mechanic handle the diagnosis and repair. This ensures that all underlying issues are identified and addressed appropriately, saving you time and money in the long run.
