Mazda CX-5 C0452: Low Fuel Tank Pressure Diagnoses

The generic OBD II code P0452 can be found in your Mazda CX-5.  It means that your CX-5’s EVAP system has detected low fuel tank pressure.

Evaporative emissions control (EVAP), which sends fuel gas from the fuel tank, to the intake manifold for burning off, is called the evaporative emission control system.  If the pressure is too low in the system, then P0452 will be generated.

If P0452 is your only code, it should not be considered as a breakdown threat. It is most often fixed by changing the fuel cap.

A bad gas cap is often the cause of P0452

The symptoms

The majority of the time, P0452 will not be associated with any visible symptoms. Your CX-5 should continue running fine.

These are the most common symptoms associated with this code.

• Check engine light (obviously)
• You can smell fuel, which indicates a loose fuel cap (or EVAP leak).
• A hissing sound is an indication of a vacuum leak

Mazda CX-5 P0452

Below are some common P0452 causes in Mazda CX-5.

• Capacity for gas is not required
• Wiring or bad fuel tank pressure sensor
• Canisters clogged with charcoal
• Vacuum leak
• Failure of the EVAP purge solenoid

Mazda CX-5 P0452 Diagnostic Procedure

Here’s a solid order of diagnosis when dealing with P0452 in your CX-5:

1. Look for other codes

Skip to next section if P0452 is your only trouble code.  If it is not, cross referencing the other code’s causes with the common causes of P0452 can really help you eliminate some possibilities.

2. Seek out the gas cap

P0452 indicates that your CX-5’s fuel tank pressure sensor has detected that the pressure in the fuel tank is too low.  This code is caused by a gas cap that isn't tight enough or not sealing well.

Take off the fuel cap.  You should pay attention to how the rubber ring fits into the fuel inlet.  A replacement will likely be required if the rubber ring is worn or dry-rotted.

OBDII code codes remain in the system until the issue is resolved.  If you believe that the fuel cap was loose, or you changed it, you’ll need to clear the code with a code scanner and see if it comes back or not.

Make sure there is nothing blocking the fuel inlet.  If it has gunk built up or mud on it, you’ll need to use a wet rag or some WD-40 to clean it off.

If it does come back, we’ll need to move on to the next step.

3. Take fuel pressure measurements

It is difficult to diagnose P0452 outside of the obvious: check the gas cap.

A mechanic would use a professional OBDII scanner to check the fuel tank pressure readings from your CX-5’s fuel tank to see if there is vacuum in the tank.

If it doesn’t look right, the wiring to the fuel pressure sensor would need to be inspected.  

If that doesn’t help anything, the tank pressure sensor itself would need to be replaced.

If everything looks fine, they’d move on to checking the EVAP system.

4. EVAP System Questions

Failures in the EVAP can result in P0452.  Here’s how a good mechanic would go about diagnosing it.  If you're going to attempt this task yourself, it is well worth the effort.

An Often Mistaken Diagnostic With P0452

People make the common error of diagnosing P0452 by doing anything without checking the gas cap.  

Or, they’ll keep going on with the diagnostic process after addressing the fuel cap because they did not clear their trouble codes.

After you have tightened the gas cap, start your CX-5 and drive it for awhile to check if the code is clear before proceeding with the diagnostics.

Mazda CX-5 K0452 Conclusion

Bad gas caps are more common than you might think.  This code can sometimes be difficult to diagnose if your gas cap works fine.