Skip the auto shop - Our mechanics make house calls

Q: outside temperature thermometer way off, a/c not working, check engine light is on

asked by on

hi there, my girlfriend has a 2015 bmw 328. she was out of town on a long weekend, and when she got back and picked up her car, which was parked in her sister's neighborhood, there were a few things acting strange:

  1. her thermometer is telling her the outside temperature is -40 F when it was actually 80 F
  2. her air conditioning isn't working
  3. her check engine light is on.

she thinks someone may have messed with her car while she was gone (she read something online that this can occur when wires are snipped)...any idea what may be causing these issues?

Thanks so much! Pat

My car has 15000 miles.
My car has an automatic transmission.

A: Hello. The reading of minus 40 degrees does...

Hello. The reading of minus 40 degrees does indicate that there is an open circuit in the sensor circuit. This will cause the A/C not to work and the Check Engine Light to come on. The sensor is in the front under the front bumper bottom cover. Look for damage underneath from hitting curb stops and you may be able to find the problem. If no damage is found, then have the sensor checked to see if rodents have chewed the wires or the sensor is damaged. If you need help having the problem scoped out, a certified technician from YourMechanic, can come to your car’s location to inspect the entire A/C system in order to have this addressed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Rear parking light not working passenger side

Filaments in bulbs can break, burn out, or come loose. The bulbs have to be tested and you can test them off the car to see if they light. If the bulbs are good, check for corrosion and/or faulty connections...

Q: No crank/no start. New battery, alternator, starter, ignition switch...

Hi there. It looks as if you have covered most of the bases. However, it is possible that you may have an exposed or faulty ground wire, damaged ignition relay or starter relay. It is also possible although unlikely, that...

Q: My car won't start. Why?

Hello. A no start condition can be caused by a few different things. If your vehicle is having issues cranking then it may be possible that there is a problem with the battery. A low or bad battery can cause...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...