Error Code P0459: What It Means & What To Do?

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The only important symptom to this problem is the Check Engine Light being on, which makes it very difficult for the driver to notice the problem. When your OBD-II equipped vehicle exhibits a code P0459, it means that the powertrain control module (PCM) has detected a problem from the evaporative emissions (EVAP) system circuit high.

When the engine starts, the purge valve on the canister opens to allow the trapped fuel vapour to be drawn by engine vacuum into the intake manifold. At the same time the vent shutoff valve also opens to allow a small amount of air to enter the canister and mix with the fuel vapour for a better mixture. Once vented and the pressure sensor in the tank shows a significant drop, both valves close sealing the system once again. The fuel vapour is routed through a vacuum line to the engine's intake and the purge valve/solenoid meters the desired amount of fuel vapours, controlled by the vehicles powertrain control module (PCM) or engine control module (ECM). The PCM/ECM monitors the voltage to the purge control valve and has detected a higher voltage than expected.

What causes this problem with the EVAP Purge Control Valve Circuit High?

• Loose gas cap
• Damaged gasket on the gas cap
• Charcoal canister damaged
• Purge control solenoid problematic
• Vacuum hoses damaged
• Fuel vapour hoses damaged
• Faulty pressure sensor
• Faulty flow sensor
• Faulty Powertrain Control Module

1. Fuel Tank Filler Neck - Is the fuel tank filler neck faulty? It’s time to replace it immediately. Buy new filler neck now!
2. Fuel Tank Vent Valve - Most of the times the vent valve doesn’t function properly causing pressure problems. Replace old valves now!
3. Vapour Canister Valve - If the vapour canister valve is faulty, it must be replaced now. Buy new canister valve from us!
4. Fuel Tank - Fuel tank must be checked for any leaks and damaged and must be replaced, if required. Buy new fuel tank from now!
5. Fuel Tank Cap - Tank cap can be faulty and wrongly installed and might require replacement. Buy new fuel tank today!
6. Diagnostic Tools - Use high quality diagnostic tools to resolve OBD code P0459 error. Buy new tools and equipment from us.

For us our customers are everything, and that’s why we will help you to diagnose P0459 code by mentioning some important symptoms below:

Common Symptoms

There is no noticeable performance difference in the vehicle, and many drivers would not notice that they have a problem until the Check Engine light comes on. Even then, it is difficult to tell what’s wrong with the vehicle. When the P0459 code appears, it is common for other trouble codes related to the evaporative emissions control system to show up as well.

Have a look at some ways with which you can correct the P0459 code:

• Fuel cap replacement
• Purge control solenoid replacement
• Charcoal canister replacement
• Fuel vapour hoses replacement
• Vacuum checks and replacement

If you need any parts to fix this problem you can easily find them with us. Not only that we also have in stock the best in range auto parts and that too at the most budget friendly prices ever online. Whether you need a Fuel Tank Filler Neck, Evaporative Vent Valve, EVAP Purge Switch, Carbon Canister, Fuel Tank, Fuel Cap you can simply rely on us for quality auto parts.

It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P0459 code to be stored:

Visually inspect the engine wiring harness connectors for damage, look for pinched wires, lose or bent pins or bare wiring with no insulation.

Check for a short to ground by disconnecting the harness at the control valve solenoid and the source of voltage. Using the DVOM set to the ohms scale, with the negative lead connected to a known good ground and the positive lead on either end that supplies power to the control valve solenoid.

If resistance is very low, suspect a short to ground and repair the wiring harness. Check for a short to ground on the control side of the harness by disconnecting the harness from the control valve solenoid and the PCM/ECM harness.

Identify the correct wire and using the DVOM set to ohms scale, check for resistance with the negative lead connected to a known good ground and the positive lead on either wire harness for the control circuit. If resistance is very low, suspect a short to ground and repair the wiring harness.

Purge control solenoid - Check for continuity at the purge control solenoid connector pins after removing the harness plug using the DVOM set to the ohms scale. Verify resistance is within manufacturers specifications. If there is a very low amount of resistance found, suspect the control valve solenoid is shorted to ground and replace with a known good unit.

Since the EVAP is only turned on during certain driving conditions, it will be necessary to monitor the EVAP control operation using an advanced scan tool capable and performing a road test under the driving conditions required to activate the EVAP system. Some advanced scan tools have an internal test to activate the EVAP system manually.

Verify the PCM/ECM is commanding the EVAP system on. If the system is functioning correctly, it will be necessary to back probe the PCM/ECM wiring harness connector using a graphing multimeter or oscilloscope with a duty cycle feature with the positive lead on the purge control valve pin and the negative lead connected to a known good ground. The duty cycle should match what is commanded on by the PCM/ECM during EVAP operation. If there is no duty cycle present, the PCM/ECM may be at fault.

Common Mistakes When Diagnosing the P0459 Code

A common problem when diagnosing and repairing the P0459 code is replacement of the evaporative emission control system when there are other issues at play. Often, dealing with a vacuum leak, or making sure that the fuel cap is on properly is all the mechanic needs to do.