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

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Cost of diagnosing the P0543 code

P0543 is a diagnostic trouble code (DTC) for "Intake Air Heater "A" Circuit Open". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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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.

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JOHNNY

33 years of experience
96 reviews
JOHNNY
33 years of experience
BMW 325Ci - Check Engine Light is on - Sacramento, California
He was great explained everything to me and have now booked him for another appointment. Thanks johnny.

Ronald

41 years of experience
93 reviews
Ronald
41 years of experience
Mercedes-Benz C300 - Check Engine Light is on - Spring, Texas
Mister Ron was very nice and took time out to explain any concerns I might have about my car. He also made sure he communicated with me when he was on his way, once he was outside, and when we was done working on my car. I appreciate that considering I have a newborn that I had to look after.

Ronald

41 years of experience
93 reviews
Ronald
41 years of experience
Ram 1500 - Check Engine Light is on - Spring, Texas
Extremely satisfied with the service, he was able to come out and diagnose almost immediately. We purchased the parts, he came back installed them and been running great since. Would definitely recommend him and will not hesitate to call again if needed.

Scott

36 years of experience
802 reviews
Scott
36 years of experience
Dodge Neon - Check Engine Light is on - Tempe, Arizona
I truly enjoy Scott as he has done work for me in the past. Scott is very friendly, knowledgeable, and a true professional! I highly recommend him.


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