P1456 – Fuel Tank Temperature Sensor Circuit Malfunction

What is the P1456 Engine Code?

The P1456 is an OBD-II generic code that stands for "Evaporative Emissions Control System Leakage (Fuel Tank System)". It indicates a very small leak detected in the fuel tank and EVAP system.

This code is specific to certain makes like Honda, Acura, Nissan, Infiniti, and Isuzu. The exact definition may vary slightly between manufacturers.

How Urgent is It?

A P1456 code does not usually affect drivability and it is generally okay to continue driving in the short term. However, it will likely cause the check engine light to come on and the vehicle will not pass an emissions test.

It's best to diagnose and repair the issue soon to ensure the EVAP system is functioning properly and to prevent potential damage to other components. If the fuel smell becomes very noticeable or fuel leaks are seen, stop driving immediately and have the vehicle towed to a mechanic.

Parts Involved

The main components of the EVAP system that can trigger a P1456 code include:

• Gas cap
• Fuel tank
• EVAP canister and vent valve
• EVAP purge control solenoid valve
• Fuel tank pressure sensor
• Connecting hoses and tubes

The EVAP system is designed to capture and prevent fuel vapors from escaping into the atmosphere. It stores the vapors in a charcoal canister and then purges them into the engine to be burned when conditions are appropriate.

Common Causes

The most common causes of a P1456 code are:

1. Loose, damaged or incorrect gas cap (very common)
2. Cracked or damaged EVAP hoses/tubes
3. Leaking fuel tank or filler neck
4. Faulty EVAP canister or vent valve
5. Bad fuel tank pressure sensor
6. Malfunctioning purge control solenoid valve

Diagnosis Steps

To properly diagnose a P1456 code:

1. Visually inspect the gas cap condition and ensure it seals tightly. Replace if damaged.
2. Smoke test the EVAP system to check for leaks in hoses, the fuel tank, and components.
3. Check the purge valve and canister vent valve for proper operation.
4. Inspect the wiring and connections to the fuel tank pressure sensor. Test the sensor itself.
5. If no obvious leaks or faults are found, more advanced diagnosis with a scan tool may be needed to pinpoint the issue.

Repair Costs

The cost to fix a P1456 code can range from under $20 for a new gas cap to over $500-$600 (400-500€) if the fuel tank or major EVAP components need replacement. Common repair costs:

• Gas cap: $10-$30 (8-25€)
• EVAP hoses: $50-$150 (40-125€)
• Purge valve: $100-$200 (80-160€)
• Fuel tank: $400-$1000+ (325-800€+)

Labor costs are usually 1-3 hours depending on the repair needed. Total repair costs are highly variable based on the root cause.

Prevention

To help prevent P1456 codes from reoccurring:

• Always tighten the gas cap until it clicks 3+ times after refueling.
• Don't top off the tank when refueling.
• Address any fuel smells or leaks immediately.
• Have the EVAP system inspected if the check engine light comes on.

By understanding the P1456 code and its causes, you can more quickly diagnose and repair EVAP leaks to keep your vehicle running efficiently and cleanly. Consult with a professional mechanic for complex issues.

Frequently Asked Questions About P1456

What does the P1456 code mean?

The P1456 is an OBD-II generic code that stands for "Evaporative Emissions Control System Leakage (Fuel Tank System)". It indicates a very small leak detected in the fuel tank and EVAP system.

What are the symptoms of the P1456 code?

Common symptoms include:

• Check engine light is on
• Slight fuel smell from the vehicle
• In some cases, no noticeable symptoms besides the code

Is it safe to drive with a P1456 code?

Yes, it is generally safe to drive in the short term as the code does not usually affect drivability. However, you should diagnose and repair the issue soon to prevent potential problems and failed emissions tests.

What causes the P1456 code?

The most common causes are:

1. Loose, damaged or incorrect gas cap
2. Cracked or damaged EVAP hoses/tubes
3. Leaking fuel tank or filler neck
4. Faulty EVAP canister, vent valve or purge valve
5. Bad fuel tank pressure sensor

How do you diagnose the P1456 code?

Key diagnostic steps include:

1. Visually inspect the gas cap condition and seal
2. Smoke test the EVAP system for leaks
3. Check the purge and vent valves
4. Test the fuel tank pressure sensor
5. Check for damaged hoses or wiring issues

Can I diagnose the P1456 code myself?

Basic checks like inspecting the gas cap and looking for obvious leaks or damage can be done at home. However, proper diagnosis requires advanced scan tools and leak detection equipment, so it's best left to professionals.

How much does it cost to fix the P1456 code?

Repair costs can range from $20 for a new gas cap to over $600 if the fuel tank needs to be replaced. Common repairs include:

• Gas cap: $10-$30
• EVAP hoses: $50-$150
• Purge valve: $100-$200
• Fuel tank: $400-$1000+

Is the P1456 code the same as a P0442?

No, while both indicate an EVAP system leak, P0442 is a generic code for a small leak detected. P1456 is a manufacturer-specific code that points to a leak in the fuel tank side of the system.

Can a loose gas cap really cause the P1456 code?

Yes, a loose, damaged or ill-fitting gas cap is one of the most common causes of P1456. The cap is part of the sealed EVAP system.

How do I clear the P1456 code?

After repairing the cause of the leak, you can clear the code with an OBD-II scanner. In some vehicles, it may clear itself after a few drive cycles if the issue is resolved.

Will the P1456 code pass emissions?

No, a car with an active P1456 code will fail an OBD-II emissions test. You must repair the issue and clear the code to pass.

Can a P1456 code come from overfilling the gas tank?

Yes, overfilling or "topping off" the tank can potentially damage the EVAP system and cause the code to appear. Always stop filling when the nozzle clicks off.

What is the EVAP system and what does it do?

The Evaporative Emission Control System (EVAP) is designed to capture fuel vapors from the tank and prevent them from escaping into the atmosphere. The vapors are stored in a charcoal canister and then purged into the engine to be burned when conditions are right.

Can a P1456 code be caused by bad gas?

It's unlikely that fuel quality would cause the code, as it points to a leak in the EVAP system. However, contaminated gas could potentially damage EVAP components over time.

How often should I replace my gas cap?

There is no set replacement interval, but it's a good idea to regularly inspect the cap for cracks, damage, or a weak seal. Replace it if you notice any issues or if the check engine light comes on.

Why does my car smell like fuel with the P1456 code?

The code indicates a small leak in the EVAP system, most likely the fuel tank or associated hoses. This can allow fuel vapors to escape, causing a noticeable smell.

Can a P1456 code cause rough idle or misfires?

Typically, the small leak detected by P1456 will not cause any major drivability issues. However, if the leak is large enough to affect the air/fuel ratio, it could potentially lead to rough running or misfires.

How long does it take to fix the P1456 code?

Diagnosis and repair time depends on the root cause. A gas cap replacement may only take a few minutes, while a fuel tank repair could take several hours.

Can I use an aftermarket gas cap to fix P1456?

It's best to use an OEM or OEM-equivalent gas cap that is designed specifically for your vehicle. Aftermarket caps may not seal properly and could cause the code to come back.

What should I do if the P1456 code keeps coming back?

If the code reappears after repair, there is likely another leak or a faulty component in the EVAP system. Further diagnosis with smoke and leak detection tests is needed to pinpoint the issue. Consult a professional mechanic for persistent problems.