P0640 OBD-II Trouble Code: Intake Air Heater Control Circuit

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

SCHEDULE P0640 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0640 code

P0640 is a diagnostic trouble code (DTC) for "Intake Air Heater Control 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 P0640 DIAGNOSTIC Get a fair and transparent estimate upfront

check engine light

P0640 code definition

When your vehicle’s PCM stores a P0640 code, it means that abnormal input voltage

has been identified as coming from the intake air heater’s control circuit.

What the P0640 code means

This means that a voltage that exceeds the level stipulated by the manufacturer has

occurred. Usually, your Check Engine Light will come on, although sometimes the code

has to be recorded three times before this happens.

What causes the P0640 code?

Most often, the P0640 code is recorded when the intake air heater relay is faulty. There

can be other causes as well, though, including:

What are the symptoms of the P0640 code?

Most of the time, there are no symptoms at all other than the Check Engine Light coming

on. You may, however, notice some loss in fuel efficiency, since the intake air heater

system works to warm the air entering the engine. If the air getting to the engine isn’t

warm enough, then you may notice a bit of a dip in your fuel economy.

Sometimes, the problem is not the intake air heater relay. Your Check Engine Light

could come on just because you have a dirty air filter.

How does a mechanic diagnose the P0640 code?

First off, your mechanic will use an OBD-II scanner and an ohmmeter to identify any

conditions that may result in a code being recorded. Next, your mechanic will:

  • Visually inspect all the wiring and connectors

  • Repair or replace any damaged wiring and connectors

  • Re-test your vehicle’s system to make sure that the replacements did the job and that everything is in proper working order

  • Connect the scanner again to make sure that the codes are no longer active

  • Test drive the car to see if the codes re-appear

  • Crank the engine and check the scanner again to make sure that the heater turns on

  • Ensure that the blower is working

  • Compare the findings with the vehicle manufacturer’s specifications

Common mistakes when diagnosing the P0640 code

Sometimes, mechanics fail to make sure that intake air temp sensors are properly

connected. This can cause a code to be improperly stored. Mechanics are also

sometimes too quick to blame the PCM itself for the problem, but the reality is that the

PCM hardly ever fails.

How serious is the P0640 code?

This is something that you can have repaired at you leisure. You may notice a slight

decrease in your engine performance, and you may also find that you are paying a little

more at the pump than you are accustomed to. However, this is not an issue that is

going to compromise your safety, or that of anyone who travels with you. It would be

a good idea to get the problem corrected, but if you have other things to do (as most of

us have), you can wait for a more convenient time.

What repairs can fix the P0640 code?

Sometimes all that is needed is to replace a dirty air filter. Other times, though, you may

need to have one or more of the intake air sensors replaced. Either way, this is not a

major maintenance or repair issue, and can be easily and economically dealt with by a

qualified mechanic.

Additional comments for consideration regarding the P0640 code

Any voltage variation that is outside the manufacturer’s specifications can lead to a

P0570 code. It doesn’t necessarily mean that anything is terribly wrong, though.

Need help with a P0640 code?

YourMechanic can assist you with any problems that relate to fuel economy, or any

other problems that you may have with your vehicle. Our qualified mechanics are

always on standby, ready to go to your home or office to help you with whatever issues

you may be having. Call us at 1-800- 701-6230, or use our online form to arrange a

visit. Our mechanics are here for you.

P0640
trouble codes
Check Engine Light

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

SCHEDULE P0640 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

3,696

Rating Summary
3,372
162
42
24
96
3,372
162
42
24
96

Bret

39 years of experience
52 reviews
Bret
39 years of experience
Very informative
1997 CADILLAC CATERA - CHECK ENGINE LIGHT IS ON - CONCORD, CALIFORNIA

Michael

24 years of experience
206 reviews
Michael
24 years of experience
Michael was prompt on time, and was able to do a check on the EPC lights that had come up on the car. He was able to narrow down the root cause and was able to recommend possible outcomes and options.
2012 VOLKSWAGEN JETTA - CHECK ENGINE LIGHT IS ON - TEMPE, ARIZONA

Matthew

30 years of experience
363 reviews
Matthew
30 years of experience
Matthew is "MyMechanic". LOL I've convinced my husband to use his services instead of going to the dealership. Thanks Matthew for you thorough review of our Jeep Commander. Matthew is friendly, knowledgeable and confident in his business. We will most definitely call him again. I have referred this service to a number of friends, have no idea if they have contacted him or not. Will giving referrals.
2006 JEEP COMMANDER - CHECK ENGINE LIGHT IS ON - NEWPORT NEWS, VIRGINIA

Dan

36 years of experience
611 reviews
Dan
36 years of experience
Dan is the best mechanic in the business.
2004 NISSAN 350Z - CHECK ENGINE LIGHT IS ON - DULUTH, GEORGIA

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...
Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...

Related questions

Q: I got code P0016 and P0008. I just want to know what caused the problem and which one is bank 1 sensor A?

Hello, this problem (both codes apply to the same problem) relates to a calculated "bad timing correlation" between the crankshaft and the exhaust camshaft for cylinder 1 (cylinder head at front of the car). Engine management has tolerances for the...

Q: When I start my car it and try to pull off it shakes and then cut off I was told it was the fuel pressure sensor which I replaced

You will need to have computer scanned for codes and supply the codes you get so I can help you better. The fuel system pressure sensor is an input for the fuel pump control module so it can control the...

Q: Getting P0107 on OBD-II, mostly when car is in reverse gear and the Check Engine Light switches on.

Hi and thanks for contacting YourMechanic. Check the manifold absolute pressure (MAP) sensor for any corrosion or burned pins. This is what the P0107 code is coming up for. Check for power to the sensor. Back probe the wires and...

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