If your Honda’s check engine light is on and you’ve pulled the code P1457, you’re probably wondering what it means. This article explains what causes the P1457 Honda code and how to fix it, giving you a clear path to getting your car back to normal.
The P1457 code is specific to Honda and Acura vehicles. It points to a problem with the Evaporative Emission Control (EVAP) system. More precisely, it indicates that the Engine Control Module (ECM) cannot bring the fuel tank pressure down to a specific vacuum level during a self-test.
In simpler terms, your car’s computer tried to check for leaks in the fuel vapor system and failed the test. It couldn’t create enough suction or vacuum. This means there’s likely a leak, a blockage, or a faulty component preventing the system from sealing properly.
What Causes The P1457 Honda Code & How To Fix It
Fixing a P1457 code requires a systematic approach. The issue is almost always within the EVAP system. This system captures fuel vapors from the tank and burns them in the engine, preventing them from escaping into the atmosphere.
When the ECM runs its test and can’t achieve the expected vacuum, it stores the P1457 code. Let’s look at the common culprits behind this failure.
Common Causes of the P1457 Code
Several components can fail and trigger this code. Here are the most frequent offenders:
- Faulty or Stuck Open EVAP Canister Vent Shut Valve: This is the most common cause. This valve, often located near the charcoal canister, is supposed to seal the system during the test. If it’s stuck open, vacuum cannot build.
- Leaking or Damaged EVAP Canister: The charcoal canister itself can crack or become damaged, allowing air to leak in.
- Clogged or Pinched EVAP Lines: The hoses and tubes that connect the system can get blocked by dirt or debris, or become pinched, preventing proper airflow and vacuum.
- Faulty Fuel Tank Pressure Sensor (FTPS): This sensor monitors pressure/vacuum in the tank. If it gives incorrect readings, the ECM may think the test failed even if it didn’t.
- Loose or Damaged Fuel Cap: While this often causes smaller leaks, a severely damaged cap or one that isn’t tightened properly can contribute to a P1457.
- Problems with the EVAP Canister Purge Valve: Although less common for this specific code, a purge valve stuck closed could theoretically prevent the system from pulling a vacuum correctly.
Diagnostic Steps Before You Start
Before replacing parts, it’s wise to do some basic diagnostics. You’ll need a scan tool that can monitor live data and possibly command EVAP system tests.
- Check the Fuel Cap: Start with the simplest thing. Remove the fuel cap, inspect the seal for cracks or damage, and re-tighten it until it clicks three times. Clear the code and see if it returns.
- Visual Inspection: Look at all the EVAP lines running from the fuel tank to the canister and to the engine bay. Check for obvious cracks, disconnections, or signs of damage. Listen for hissing sounds near the canister when the system is testing.
- Use a Smoke Machine (Professional Tool): The most effective way to find an EVAP leak is with a smoke machine. Smoke is pumped into the system, and where it escapes, you find your leak. This is often done at a shop.
How to Test the EVAP Canister Vent Shut Valve
Since this valve is a prime suspect, testing it is a key step. It’s usually found underneath the car, near the charcoal canister behind the rear wheels.
- Locate the valve. It’s a small black plastic component with two hoses and an electrical connector.
- With the engine OFF, disconnect the electrical connector.
- Use a multimeter to check the valve’s resistance across its two terminals. You should typically get a reading between 20-40 ohms. An infinite reading (open) or zero (short) means the valve is bad.
- You can also apply 12 volts directly from the car battery to the valve terminals (mind the polarity). You should hear a distinct click as it opens and closes. No click means it’s stuck.
- With the valve disconnected, try blowing air through the ports. When no power is applied, it should be closed (no air flow). When powered, it should open (air flows). If it’s stuck open, air will flow all the time, confirming the fault.
Step-by-Step Repair Guide
Once you’ve identified the likely faulty component, you can proceed with the repair. Always disconnect the negative battery cable before starting work for safety.
Replacing the EVAP Canister Vent Shut Valve
- Safety first: Ensure the car is on a level surface, the parking brake is engaged, and the battery is disconnected.
- Locate the valve. You may need to raise and safely support the rear of the vehicle.
- Label or take a picture of the hose connections to the valve to ensure proper reinstallation.
- Disconnect the electrical connector by pressing the tab and pulling it off.
- Use a small flat-head screwdriver to loosen the hose clamps, then carefully pull the hoses off the valve.
- Remove the valve from its mounting bracket (this might involve a simple clip or a bolt).
- Install the new valve in the reverse order. Double-check that all hoses are connected securely and the electrical connector is fully seated.
- Reconnect the battery, clear the diagnostic trouble codes with your scan tool, and perform a test drive to allow the ECM to run its self-test cycle.
Addressing Other Common Causes
For a Leaking Canister: The replacement process is similar to the valve. The canister is usually held by a bracket or strap. Disconnect all hoses and the electrical connection to the attached valve, unbolt it, and swap in the new unit.
For Damaged EVAP Lines: Replace any cracked or brittle hoses with OEM or equivalent quality fuel/EVAP line. Make sure connections are tight and the routing is correct to avoid pinches.
For a Faulty Fuel Tank Pressure Sensor: This sensor is usually on top of the fuel tank or in the EVAP line. Access can be tricky. After depressurizing the system, disconnect the electrical connector and the hose, then unthread or unclip the old sensor to install the new one.
After the Repair: Clearing the Code and Completing the Drive Cycle
Simply fixing the problem won’t turn off the check engine light. You need to clear the code. Use your OBD2 scan tool to clear the DTCs from the ECM’s memory.
After clearing, the monitor for the EVAP system will be “incomplete.” To verify the fix, you must complete a “drive cycle.” This lets the ECM run all its self-tests again.
A typical drive cycle involves driving at various steady speeds (like highway and city driving) for a certain period, sometimes with a cold start. When the conditions are met, the ECM will run the EVAP test. If it passes, the monitor will show “complete” and the light will stay off.
FAQs About the P1457 Code
Is it safe to drive with a P1457 code?
Yes, you can usually drive the car, but you should adress it soon. The problem is with the emissions system, not the engine’s core operation. However, you may fail an emissions inspection, and a large leak could theoretically affect fuel economy slightly.
Can a loose gas cap cause a P1457?
It can contribute, but P1457 usually indicates a larger leak or a complete failure to seal. A loose cap more commonly causes smaller leak codes like P0455 or P0457. Still, always check and tighten the cap first.
How much does it cost to fix a P1457 code?
Costs vary widely. If it’s just the vent shut valve, the part might cost $50-$150, and labor could be 1-2 hours ($100-$300). If the canister needs replacing, parts and labor can range from $200 to $500 or more at a dealership. DIY repair significantly cuts costs.
Why does the code keep coming back after I fix it?
If the code returns, you likely haven’t found the primary fault. There could be another, smaller leak elsewhere in the system, a wiring issue with the valve (like a broken wire causing intermittent operation), or a faulty ECM (very rare). A thorough smoke test is the best next step.
What’s the difference between P1457 and P1456?
They are closely related. P1456 also indicates an EVAP system leak but is typically for a “very small leak.” P1457 is for when the system fails to achieve vacuum at all, pointing to a larger leak or a complete component failure. The diagnostic process is very similar for both.
Dealing with a P1457 code on your Honda can be frustrating, but it’s a very fixable problem. By understanding the system and methodically checking the common causes—starting with the EVAP canister vent shut valve—you can diagnose and repair it yourself. Remember to always start with a visual inspection and simple checks before replacing parts. With a little patience, you can solve this issue and get your Honda’s check engine light turned off for good.