P1450 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.

Meaning

The Diagnostic Trouble Code (DTC) P1450 is the error code that is displayed when the evaporative emission (EVAP) running loss monitor detects an inordinate vacuum in the fuel tank when the engine is working. This occurs when the Powertrain Control Module (PCM) fails to maintain a specific vacuum value in the EVAP system and the engine is running at a speed beyond that of the idling RPM (Revolutions per Minute).

The Evaporative Emission Control System (EVAP) functions to capture and store fuel vapors before they escape into the atmosphere. The captured vapors are stored temporarily inside the charcoal canister where they remain until the PCM initiates the discharge of the stored vapor into the engine vacuum through the purge valve. Also, a vent valve is attached to the EVAP system to allow for fresh air into the system when the stored vapor is being discharged.

Normally, the vent valve is expected to remain open for effective discharge of the stored vapor, while the purge valve which normally remains closed, is opened and closed by the command from the PCM for the discharge of vapor from the EVAP system. However, when abnormalities occur and the vent valve is closed, this will block the inlet of air through the vent valve and the charcoal canister, thereby obstructing the airflow in the system, and as a result, a vacuum above the stipulated value is accumulated when the purge valve is opened to discharge the stored vapors.

Error P1450 is displayed and the check engine light is ignited when the high vacuum is maintained above 60 seconds.

Causes

Several factors could cause your vehicle to give a P1450 error code; the most common of these are:

• Obstruction of the evaporative emission (EVAP) canister or the vent solenoid;
• Impeded movement of fuel vapor from the fuel tank to the EVAP resulting from a defective connecting hose;
• Defective or faulty fuel tank pressure sensor;
• Obstructed vacuum relief resulting from stuck fuel filter cap;
• Defective, corroded, or shorted wiring and connectors;
• Faulty charcoal canister resulting from overfilling of the fuel tank.

Symptoms

The P1450 only has a few symptoms attributed to its effects on a vehicle, and these symptoms, unlike some other OBD-II errors, do not pose threat to the drivability of the vehicle but registers the error in the vehicle’s memory. These symptoms include:

• Illumination of the check engine light; and
• Delay in engine start-up time after filling the tank which occurs in rare cases.

Diagnosis

Diagnosing OBD-II errors can be technical and pose difficulty for beginners, hence, we recommend allowing only certified and professional mechanics to diagnose your vehicle. Nevertheless, these simple steps are excellent ways to diagnose P1450:

• Start the diagnostic process by inspecting the EVAP canister and the vent solenoid for possible blockage in the system;
• Next, check the hose connecting the fuel tank with the EVAP for possible fault or defect;
• Should there be any defect in the hose, replace the hose and ensure it is properly connected;
• Proceed to check if the fuel tank cap is stuck. Fix or replace the cap as appropriate;
• Inspect the fuel tank pressure sensor and repair or replace if faulty;
• After completing the steps above, clear the error code and check if the code returns;
• If the code returns, proceed to download and read freeze frame data on the PCM;
• Then, conduct a visual inspection on all wirings, connections, hoses, and fuel lines connecting to the EVAP and its components. For the adequacy of this information, use the instructional manual to locate all the components of the EVAP system;
• Tighten loose connections in the EVAP system and repair or replace any faulty parts;
• If the error persists after the necessary repairs and replacement of all the EVAP components, or if no visible damage is found, test the valves’ control unit circuit for ground connectivity, resistance, and continuity. Kindly consult the manual guide of the car to do that;
• Having done that, compare the reading you get with the readings specified in the manual, then repair and replace faulty parts as appropriate;
• Alternatively, if the OBD-II scanner has a control function, use the scanner command to check if the vent valve is opened. However, this particular scan will only check the openness of the valve;
• If the vent seems to be working fine after the scan, it probably means there is a blockage in the connecting tubes of the vent valve;
• If the blockage is detected in the connecting tube, remove the blockage or replace the tube if necessary;
• If the error persists after the steps above, remove the charcoal canister and inspect for possible damage. A quick way to detect a damaged charcoal canister is by shaking it, if defective, water, fuel, or charcoal granules will fall off during the shake;
• In this case, the only solution is to replace the canister;
• Meanwhile, if no fault is detected in the canister and the vent valve, remove all vacuum hoses located in between the canister and the fuel tank that is related to EVAP;
• Then check for possible blockages and leaks in the hoses and clean or replace them if not sure of their condition;
• Lastly, clear the P1450 code and conduct another test on the system to see if the error is cleared.

Common Mistakes

Failure to properly inspect all the components, wirings, hoses, and connections of the EVAP system, the charcoal canister, and/or the fuel tank is a common mistake often made by mechanics during the process of diagnosing P1450. 

In most cases, it is possible to fix the code by simply cleaning the system or removing the blockage within the connecting hoses instead of part replacement.

How Serious Is P1450?

The P1450 error code is not a serious error code as it does not have any drivability issue or cause further damage to the vehicle’s engine through persistent use. Nevertheless, it is not advisable to leave OBD-II errors in your vehicle without being fixed.

What Repair Can Fix P1450?

There are some other repairs that can be carried out on a vehicle with the P1450 trouble code and these repairs are quite simple and straight forward, they include

• Repairing or replacing the fuel filler tube;
• Removing obstructions of the hoses connected to the EVAP system, or change the hoses if removing obstructions will not solve the problem;
• Replacing of the charcoal canister.

Conclusion

Conclusively, diagnosing P1450 is not some easy DIY for novices, furthermore, dealing with this error code as well as other OBD-II errors should be done with care by experts to void further complications in the vehicle.