P0540 OBD-II Trouble Code: Intake Air Heater "A" Circuit

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0540 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0540 code

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 for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0540 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light P0540 OBD-II Trouble Code: Intake Air Heater "A" Circuit

Diagnostic Trouble Code (DTC): P0540

P0540 code definition

The presence of the P0540 code in the PCM means that an abnormal input voltage was detected from the intake air heater circuit.

What the P0540 code means

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.

What causes the P0540 code?

The most frequent causes of the P0540 code include a faulty intake air heater relay, as well as the following causes:

  • Shorted, open, or corroded wiring or connectors
  • Burnt out heater elements
  • Bad intake air heater blower
  • Faulty intake air temperature sensor
  • Disconnected intake air temperature sensor
  • Faulty PCM, in rare cases

What are the symptoms of the P0540 code?

Usually, the only discernible symptoms will be the stored trouble code and the illumination of the Check Engine Light.

How does a mechanic diagnose the P0540 code?

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.

Common mistakes when diagnosing the P0540 code

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.

How serious is the P0540 code?

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.

What repairs can fix the P0540 code?

In order to address the P0540 code, a service technician may perform any of the following repairs:

  • Replace a faulty intake air heater
  • Repair shorted, open, or corroded wiring or connectors
  • Replace burnt out heater elements
  • Replace a bad intake air heater blower
  • Replace a faulty intake air temperature sensor
  • Reconnect a disconnected intake air temperature sensor
  • Replace a faulty PCM, in rare cases

Need help with a P0540 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.

Check Engine Light
trouble codes
P0540

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0540 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

4,004

Rating Summary
3,661
169
45
25
104
3,661
169
45
25
104
Pete

Pete

13 years of experience
174 reviews
Pete
13 years of experience
Pete was polite, knowledgeable and patient throughout all our questions.
1997 VOLKSWAGEN CABRIO - CHECK ENGINE LIGHT IS ON - LAKESIDE, CALIFORNIA
Richard

Richard

18 years of experience
451 reviews
Richard
18 years of experience
Very knowledgeable and friendly!
2008 BMW 528I - CHECK ENGINE LIGHT IS ON - ATLANTA, GEORGIA
Michael

Michael

11 years of experience
57 reviews
Michael
11 years of experience
Can't say enough about Michael, but what I will say is thank god I found him. He's a great Mechanic honest and very professional. He's on time and knows his trade. This is the second time he worked on my car and very happy with his work. He's a gem! Best of all he comes right to you, your home or office. Thanks so much!
2007 DODGE CALIBER - CHECK ENGINE LIGHT IS ON - SUFFERN, NEW YORK
Rusty

Rusty

20 years of experience
263 reviews
Rusty
20 years of experience
Rusty fixed what another company had messed up on my truck last year. He was quick and very professional. I love the convenience of having my car worked on at my house. Nobody is trying to hide anything by "not allowing you in the service department area". I don't need a loaner car, Im at home with my own things so Im comfortable. Best of all, I don't waste any time driving to a garage, getting a car, driving back to get my car and paying outrageous prices while still not having things fixed. Rusty is a great asset to the company.
2002 DODGE RAM 1500 - CHECK ENGINE LIGHT IS ON - KENNEDALE, TEXAS

More related articles

The Traveler’s Guide to Driving in Malaysia
CraigBurrows / Shutterstock.com Malaysia is a popular destination for many tourists today. The country has amazing sights and attractions that you will want to explore....
How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...

Related questions

Q: P0455 Code

The code P0455 is an indication that the fuel system cannot hold vapor pressure when it is put into testing. This means you have a leak somewhere. Since you did not have the issue before you had worked on the...

Q: Co2 sensors are detected as malfunctioning . Can I still drive with this problem until i can afford to fix. 1 week.

The codes you are getting may be directed to the O2 sensors but can be caused by a computer system or fuel system malfunction. You should get each code diagnosed to find out what is the cause of the rich...

Q: The check engine light always seems to come on when my gas tank is half full. 1998 Honda Accord

Hello - the first task here is to capture the problem codes turning on the Check Engine light. Most auto parts stores will do this for free - on a time-available basis. It is probably worth checking for problem codes...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com