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P0540 is a diagnostic trouble code (DTC) for "Intake Air Heater "A" Circuit". 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.
P0540 OBD-II Trouble Code: Intake Air Heater "A" Circuit
The presence of the P0540 code in the PCM means that an abnormal input voltage was detected from the intake air heater circuit.
The intake air heater is used to warm air so that cylinder combustion happens correctly. During cold operation, the ECM grounds the control coil of the intake air heater relay in order to energize the heater. If the voltage reading from the ECM exceeds the manufacturer’s specifications during this process, the PCM will store the P0540 code.
The most frequent causes of the P0540 code include a faulty intake air heater relay, as well as the following causes:
Usually, the only discernible symptoms will be the stored trouble code and the illumination of the Check Engine Light.
The diagnostic procedure for the P0540 code begins with verifying the code using an OBD-II scanner. Afterwards, all electrical components should be visually inspected to ensure that they are connected and not in need of replacement or repair. After this step, it is important to clear the trouble code from the PCM, and retest the system. If the code returns, the issue likely lies with the intake air heater or the temperature sensor. In addition to an OBD-II scanner, an infrared thermometer, and a digital volt reader will be necessary to properly diagnose this issue.
Often when a mechanic replaces an air filter, or removes the air cleaner box during other repairs, the intake air temperature sensor may not be reconnected correctly. This can cause the P0540 code to be stored, and should always be checked before replacing any parts.
While little to no symptoms may be observed with the P0540 code, it is still an important issue that must be repaired immediately. If the issue is not addressed, the vehicle may lose the ability to start altogether.
In order to address the P0540 code, a service technician may perform any of the following repairs:
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