P0533 code definition

The P0533 code shows when the signal circuit in the vehicle is detected to be too high.

What the P0533 code means

If the P0533 code is being displayed, that means the air conditioning refrigerant pressure in your vehicle is probably too high to safely function. Although it’s related to the air conditioning, if you’re driving in a cold winter climate, you could still see the code because AC is used for defogging your vehicle.

Simply put, the AC unit works as a heat pump. It removes warm air from inside your vehicle and transfers it outside by using radiators, a system of fans and a compressor. The key behind the whole system is the refrigerant – usually R-134a – which is responsible for using airs and tubes to circulate the air.

The ECM (Engine Control Module) monitors the AC unit, primarily assessing the refrigerant pressure. If it becomes too high or too low, the ECM will lock out the AC function completely in order to keep the compressor and the entire system from becoming damaged.

What causes the P0533 code?

There are a handful of common reasons your vehicle could be showing the P0533 code.

What are the symptoms of the P0533 code?

If your AC refrigerant pressure sensor circuit is sensing high input, the Check Engine Light should come on. You’ll most likely also notice that the air conditioning has become completely inoperative or is only blowing out warm air.

How does a mechanic diagnose the P0533 code?

The mechanic will use an OBD-II scanner, connecting it to the diagnostic connector, recording all stored codes and freeze frame data. They’ll then clear the codes and test drive the vehicle to see if the AC works and/or if the code comes back.

They will then use pressure gauges to test the AC by turning on the engine and putting the air conditioning on high. If the gauge shows a reading that falls below 29 psi and the compressor clutch engagement isn’t on, the mechanic will most likely just be able to add more refrigerant to solve the problem.

Common mistakes when diagnosing the P0533 code

As we just mentioned, it’s a mistake to assume that the sensor in charge of triggering the P0533 code is automatically accurate. This is why mechanics must examine it before assuming another problem exists and proceeding with repairs.

How serious is the P0533 code?

The P0533 code isn’t a sign that your life is in danger. At worst, your air conditioning simply won’t work. However, until a qualified mechanic addresses the issue, you’ll have a tough time staying cool during hot weather or using your defogger.

What repairs can fix the P0533 code?

  • The first thing a mechanic will most likely do is measure the refrigerant pressure by using manifold gauges.
  • They will then move on to looking for mechanical issues like damaged lines, moisture, leaks, or some type of blockage.
  • The pressure sensor should also be examined as it could simply be malfunctioning and there is no actual problem with the refrigerant.

Additional comments for consideration regarding the P0533 code

In some cases, you may simply be able to turn your vehicle off and back on, at which point the system will retest itself and activate the air conditioning if pressure is no longer a problem.

Need help with a P0533 code?

YourMechanic provides customers with certified mobile mechanics who will come to your home or office, diagnose your vehicle and repair any problems. Complete our online form or speak to a service advisor by calling 1-800-701-6230. We’ll provide you with a free quote and have a mechanic to your home or office right away.

This article originally appeared on YourMechanic.com as P0533 OBD-II Trouble Code: A/C Refrigerant Pressure Sensor Circuit High Input and was authored by Valerie Johnston.


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