Fault code P0451 – evaporative emission control system pressure sensor range/performance

Fault code P0451 is called “Evaporative Emission (EVAP) Control System Pressure Sensor Range/Performance” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0451

This diagnostic trouble code (DTC) is a generic code. Error P0451 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P0451 – evaporative emission control system pressure sensor range/performance

The code indicates that part of the EVAP control system is no longer functioning properly. The EVAP system consists of many parts, including (but not limited to) the tank cap, fuel lines, carbon tank, air valve, and others.

The emission control system (EVAP) prevents fuel vapor from escaping from the vehicle’s fuel system. Fuel vapors are routed through hoses to a carbon canister for storage. Later, when the engine is running, the purge control valve opens, allowing fuel vapors to be drawn in under vacuum.

The EVAP canister purge is controlled by a valve that allows fuel vapors to be drawn in due to the vacuum created by engine operation. They flow from the fuel tank into the engine for combustion, rather than escaping into the atmosphere.

The EVAP pressure sensor allows the PCM to monitor the pressure in the EVAP system. It is almost always in the fuel tank and is built into the fuel pump housing.

If the EVAP and fuel tank pressures are not within the operating range programmed by the manufacturer. Within a specified period of time and under certain circumstances. Code P0451 will be stored and the Malfunction Indicator Lamp (MIL) may illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P0451 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be written in the ECM memory as a fault).
  2. Fuel odor may be present in some cases.
  3. A slight decrease in engine performance.
  4. A slight increase in fuel consumption.
  5. In most cases, you will not notice any symptoms other than a lit control lamp (MIL).

The severity level of code P0451 is medium. The car will be able to continue driving, but the harmful emissions will increase. Which, in practice, will not allow the vehicle to pass the emission test.

Factors that can cause this error code

The error code P0451 can mean that one or more of the following problems have occurred:

  • EVAP pressure sensor is defective.
  • Broken wiring harness.
  • Shorted or broken connector.
  • Corrosion or resistance in connector.
  • Fuel tank safety valve is clogged.
  • Unusually high pressure in fuel tank due to clogged EVAP hose.
  • Cracked or broken charcoal canister.
  • Sometimes the cause is a faulty PCM module.

How to fix or reset OBD-2 code P0451

Some suggested steps for troubleshooting and fix the error code P0451:

  1. Repair damaged EVAP lines.
  2. Repair open or shorted voltage supply circuit to EVAP pressure sensor.
  3. Repair circuit going to PCM.
  4. Repair or clean the connector.
  5. Replace the EVAP pressure sensor.
  6. Repair or repair the restriction in the EVAP line.
  7. Replace PCM if the situation requires it.

Diagnose and repair of problems

Check that all EVAP hoses are connected correctly and in good condition. Check wiring harnesses for obvious damage, due to fraying or improper routing. Inspect electrical connectors for corrosion, pins should be straight and properly installed.

Make sure that the tank lid gasket is in good condition and the lid is properly installed . After that, clear code P0451 and test drive to see if the error returns again.

If the tank cap gasket is cracked, crushed, or otherwise damaged, replace it.

Make sure that the bleed hose that carries fresh air into the canister is not blocked, clogged or crushed. If insufficient air is drawn in during the purge cycle, this could set off this fault code.

Visual inspection

Because code P0451 is a general fault code, it can often be related to damaged or corroded wiring. Also with a faulty or disconnected sensor.

Locate the EVAP canister under the vehicle. It may be attached to the fuel tank or be separated from it by the hoses going to the fuel pump. Make sure that the EVAP control pressure sensor connector is fully inserted and secured.

Inspect the connector for corrosion, disconnect the sensor and inspect the terminal pins. To make sure they are clean and free of moisture. Inspect the wiring from the sensor to determine if there are any tears, blows on the wire insulation. Which may indicate corrosion inside the wire.

Check the voltage on the sensor

Make sure there is 5 volts on the test lead, and check for continuity of the ground circuit. Check the sensor signal wire with a multimeter to determine the voltage, it should be about 3 volts.

Remove the hose attached to the EVAP pressure sensor and create a vacuum with a vacuum gauge, monitoring the voltage changes on the multimeter. If the voltage changes when the vacuum is applied, the sensor is working. If the voltage does not change, the sensor is defective.

Perform a wiggle test to determine if there is a problem. By jiggling or wringing the wires, watch the readings on the multimeter to see if there are voltage fluctuations. If the voltage rises or drops sharply when you turn a section of wire, you probably have a break that needs to be repaired.

If the jiggle test fails, disconnect the EVAP pressure sensor and check the voltage. If the voltage remains high with the sensor disconnected, check the wiring harness for a shorted signal wire.

If the reference voltage and ground readings are good, a faulty EVAP pressure sensor is most likely the problem. Therefore, you will have to replace it to correct error P0451.

There are times when the sensor is disconnected that the high voltage is gone, the grounding circuit is good, and the reference voltage is correct. This indicates that the EVAP purge hose is clogged. Disconnect the hose from the purge valve and blow it out with compressed air. If the clog cannot be cleared, replace the hose.

On which vehicles does this problem occur most frequently

Fault code P0451 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi
  • Buick (Rendezvous)
  • Cadillac
  • Chevrolet (Silverado, Tahoe)
  • Dodge (RAM)
  • Ford (Edge, Escape, Explorer, F-150, Fusion, Mustang, Taurus)
  • GMC (Sierra)
  • Hyundai (Accent, Elantra, Sonata)
  • Infiniti
  • Kia (Sportage)
  • Lexus (GX470)
  • Mazda
  • Mercedes-Benz
  • Nissan
  • Subaru
  • Toyota
  • Volkswagen
  • GAZelle (Valdai)

Fault code P0451 can sometimes be found with other errors. The most common are the following: P0132, P0191, P0328, P0446, P0450, P0452, P0453, P0454, P0455, P0456, P0457, P0458, P0459, P0496, P1450.

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