What is the P0543 fault number? What is the explanation for the Intake Air Heater “A” Circuit Open fault? How do I fix the P0543 fault code What are the symptoms and causes for the P0543 fault code
What is the P0543 fault code? What does it signify?
If the powertrain control unit (PCM) is receiving an abnormally high voltage signal via the intake air heater “A”, and it is unable to properly control the system at the specified times, it may assume that there has been a fault in the system and assign fault code P0543.
A typical intake heater system includes a heating element and a fan motor that heats the air. It also contains a relay, temperature sensor, wiring, connectors and other electrical components. Hot air must be directed to the inlet via air ducts. Although the design of intake air heaters is different, their job is the same. They heat the air that has been drawn into the engine in order to improve the combustion function during cold starts. Since the hot air-fuel mixture burns faster than the cold mixture, the volume of heated water decreases and the vehicle’s fuel consumption and emissions are decreased. The temperature at which the heating system is activated must be below the set level by the manufacturer.
The PCM will command the heater “On” when the engine coolant temperature drops below 40°C (104°F). Through a relay, the battery supplies the electrical voltage to the heater. The PCM sets fault code P0543 when it senses that the heater’s voltage signal is too high.
You should note that heating the intake air may not be possible in all vehicles. To compensate for the lower air density, these vehicles send additional fuel. This leads to increased fuel consumption and emissions.
The P0543 fault code can affect vehicles of all makes and models, including but not limited to: BMW, Ford, Cadillacs, Toyota, Suzuki. Isuzu, Jeep. Chrysler, Dodge. Chevrolet. GMC. Honda.
What causes the P0543 Fault code?
This code is usually caused by the IAT sensor not being properly connected after the filter has been replaced or removed for repairs. Before replacing any part, it is important that you check the sensor.
Fault code P0543 is most commonly triggered by the following:
- – Defective heater relay
- – Broken, melted or ruptured wires for heater “A”, circuit, or loose, corrosiond connectors
- – The heater’s electrical components are molten or burned.
- – Heating element defect
- – Defective fan motor
- – Air ducts that are damaged or blocked
- – Sensor for defective intake air temperature (IAT).
- Problems with IAT sensor connectors and cables
- – The PCM is defective or must be reprogrammed. This happens very rarely
What are the symptoms of the P0543 Fault Code?
Code P0543 usually only causes the check engine light to come on. Rarely are serious symptoms that affect vehicle driving seen. You may experience different issues at sub-zero temperatures.
These symptoms may be present in vehicles with code P0543.
- – Illumination for the check engine light
- – Extended cranking times
- – Increased idle speed or stalling after the engine has cooled.
- – A slight rise in fuel consumption
- – IAT sensor fault codes can be set
How do I fix the P0543 fault code?
All wiring, relays, and electrical components that connect to the heater must be examined before diagnosing the code P0543. The codes should be cleared after any intervention and the vehicle should then be tested again to determine if it has returned. If the code does not return, it is likely that the problem is with the intake heater or temperature sensor.
The following repairs may be able to resolve the P0543 fault code:
- Repairing a damaged heater relay
- Repair of damaged, melted or corroded wires, connections, and all electrical parts causing an open/shortcircuit to the heater/IAT sensor
- – Replacing an inefficient intake air heater
- – Replacing a defective intake air temperature sensor
- – Replacing the damaged fan motor
- – Repair and replacement of damaged or restricted air conduits
- – Reprogramming or replacement for a defective PCM
How serious is the P0543 fault code?
P0543 is a serious problem which must be addressed, even if there are no signs that it could compromise driving safety. The vehicle could experience an increase in fuel consumption or a decrease of engine performance if the problem is not fixed. The engine might not start in extremely cold conditions. Inefficient combustion of fuel can lead to excessive carbon buildup. It is best to have the problem diagnosed promptly and fixed as soon as possible.
