Skip the auto shop - Our mechanics make house calls

P0543 OBD-II Trouble Code: Intake Air Heater "A" Circuit Open

check engine light

P0543 code definition

Detecting the P0543 code indicates that the PCM is reading an abnormal amount of input voltage from the intake air heater circuit.

What the P0543 code means

The engine control module, or ECM, uses an intake air heater that warms incoming air in order to achieve proper cylinder combustion. The ECM detects the voltage on the intake air heater circuits in order to determine that the heater is performing correctly. If the voltage is too high, the ECM assumes that the heater is in the open position when it isn’t meant to be, and will alert the PCM to store the P0543 code.

What causes the P0543 code?

The most common underlying issue for the P0543 code is a faulty intake air heater relay.

Other causes may include:

What are the symptoms of the P0543 code?

In most cases, the only symptoms will be the P0543 code stored in the PCM, and the illumination of the Check Engine lamp.

How does a mechanic diagnose the P0543 code?

After an OBD-II scanner detects the P0543 code, the first diagnostic step taken should be a visual inspection of all the wiring, connectors, and other electrical components. Any damaged elements should be replaced, reconnected, or repaired as necessary. Once this procedure is complete, the mechanic should then clear the code and test the system. If the code returns, they have successfully diagnosed an issue with the intake air heater and/or its circuit.

Common mistakes when diagnosing the P0543 code

In many cases, technicians or vehicle owners replace dirty air filters, or remove the air cleaner box for repairs, during a tune up, and do not reconnect the intake air temperature sensor correctly. It is common for some mechanics to begin replacing the intake air heater relay or other parts, before checking if a bad connection is the underlying issue.

How serious is the P0543 code?

If the P0543 code is being detected, the issue needs to be addressed right away. The vehicle’s ability to create the proper environment for cylinder combustion is vital to the overall operation, making this a very serious malfunction. Even though no symptoms may be present, it is important to have this repair performed right away when detected.

What repairs can fix the P0543 code?

There are many ways that a technician can address a P0543 code detection. They include:

It is important that after each repair, the mechanic clear the code from the PCM and preform a system test. If the code returns during the test, the previous repairs did not address the issue, and the mechanic must continue with diagnostics and repair. This process helps mechanics to pinpoint exactly what caused the issue in the first place, which can make future repairs much easier should the issue arise again.

Need help with a P0543 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...


Related questions

Q: will a temperture switch cause an engine not to start?

The engine coolant temperature sensor sill not cause the engine to die or not start, but can cause the fuel system to go full rich. The engine dies when getting hot is most likely due to an ignition spark loss...

Q: Hi. I o I've got various codes to do with air flow to the engine. I changed all spark plugs and the main air sensor with no result

Hello, and thank you for writing in. There are several air intake and exhaust sensors that your codes may be pertaining to. Without the actual codes to help diagnose the problem it is difficult to tell. There are air intake...

Q: What means error fault code p1978

The trouble code you listed is a manufacturer specific code, designated by the P1xxx. I have searched my files and cant find that DTC trouble code. Can you please verify that the code is P1978? However, if you'd like to...