What does it mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles (Dodge, Ram, Ford, GMC, Chevrolet, VW, Audi, Toyota, etc.). Although generic, specific repair steps may vary by make/model.
When your OBD-II equipped vehicle stores a P0454 code, it means the Powertrain Control Module (PCM) has detected an intermittent signal from the Evaporative Emission System (EVAP) pressure sensor circuit.
To capture fuel vapors before they escape into the atmosphere, the EVAP system uses a vented storage tank (commonly called a canister) to store excess fuel vapors until the engine is operating under appropriate conditions to burn them efficiently.
Vapors from the fuel storage tank are evacuated through the pressure relief valve (atop the fuel tank). The pressure created when fuel is stored acts as a propellant and causes vapor evacuation through a network of metal tubes and rubber hoses; ultimately reaching the charcoal storage canister. The canister not only absorbs fuel vapors but also holds them for release at the appropriate time.
The typical EVAP system consists of a charcoal canister, EVAP pressure sensor, purge valve/solenoid, vent control valve/solenoid, and a complex system of metal tubes and rubber hoses extending from the fuel tank to the engine compartment.
The purge control valve/solenoid, which is the hub of the EVAP system, is electronically controlled by the PCM. The purge control valve/solenoid is used to regulate intake vacuum in the EVAP canister so fuel vapors are drawn into the engine when conditions are ideal for them to be burned as fuel instead of polluting the atmosphere.
EVAP pressure is monitored by the PCM using the EVAP pressure sensor. The EVAP pressure sensor can be difficult to access as it’s typically located atop the fuel tank and integrated into the fuel pump/fuel level sender unit housing. If the PCM detects that the EVAP system pressure signal is intermittent, a P0454 code will be stored and the Malfunction Indicator Lamp (MIL) may be illuminated.
Evaporative emission related trouble codes include P0450, P0451, P0452, P0453, P0455, P0456, P0457, P0458 and P0459.
Code Severity and Symptoms
Symptoms of this code may include:
In most cases, no symptoms will present with P0454
Slight decrease in fuel efficiency
MIL illumination (malfunction indicator lamp)
Causes
Possible causes for this code being set include:
Faulty EVAP pressure sensor
Clogged fuel tank pressure relief valve
Open or shorted wiring or connectors in EVAP pressure sensor circuit
Cracked or broken charcoal canister
Diagnostic and Repair Procedures
If I need to diagnose a P0454 code, I know I’ll need a diagnostic scanner, digital volt/ohmmeter, reliable vehicle information source like All Data DIY, and possibly even a smoke machine.
A visual inspection of EVAP system hoses, lines, wiring harnesses and connectors is a good place to begin your diagnosis. Pay particular attention to components routed near sharp edges or hot exhaust components. Remember to remove the fuel tank cap, inspect the seal, and reinstall it properly.
Next, I like to continue by connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and freeze frame data. It’s a good idea to document this information as it can prove very helpful, especially if this is an intermittent code. After that, I like to clear the codes and test drive the vehicle until it enters OBD-II readiness mode or the code resets. EVAP codes typically require multiple drive cycles (with a failure in each) before being reset.
Observe the EVAP pressure sensor signal using the scanner’s diagnostic data stream. I know I’ve corrected the situation (by tightening or replacing the fuel cap) if system pressure meets manufacturer recommended specifications.
Before performing a smoke test, I would test the EVAP pressure sensor since this is an intermittent pressure sensor circuit code. The EVAP pressure sensor location can complicate testing as it’s typically located atop the fuel storage tank. After accessing the sensor, follow manufacturer recommendations for testing and replace the sensor if it doesn’t meet specifications.
Disconnect all associated controllers and test individual circuits with the DVOM if the EVAP pressure sensor meets manufacturer specifications. Repair or replace open or shorted circuits as necessary and retest the system.
Additional diagnostic notes:
Low or high EVAP pressure can result in P0454 storage
This code can be caused by electrical or mechanical malfunctions