B1946 OBD-II Trouble Code: Climate Control A/C Post Evaporator Sensor Circuit Failure

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

SCHEDULE B1946 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the B1946 code

B1946 is a diagnostic trouble code (DTC) for "Climate Control A/C Post Evaporator Sensor Circuit Failure". 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 $79.99. 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.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$79.99$20.00
Toyota$79.99$20.00
BMW$79.99$20.00
SCHEDULE B1946 DIAGNOSTIC Get a fair and transparent estimate upfront

diagnostic check engine light

B1946 code definition

The B1946 code is a manufacturer specific body code related to the climate control system. In this case, the engine control module (ECM) has detected a failure in the evaporator temperature sensor for the climate control system or A/C.

What the B1946 code means

A code B1946 will be stored when the ECM detects a voltage signal from the post evaporator sensor that is signalling a failure (the signal should be approximately 5 volts depending on vehicle make and model).

Under normal operation, the LH and RH discharge temperature sensors receive a ground from the Dual Automatic Temperature Control (DATC) module. The evaporator discharge temperature sensor receives a ground from the DATC module. A 5-volt reference voltage is supplied to the LH and RH discharge temperature sensors from the DATC module. A 5- volt reference voltage is supplied to the evaporator discharge temperature sensor from the DATC module.

What causes the B1946 code?

Several problems may cause a B1946 code including:

  • Malfunctioning, damaged, or defective evaporator temperature sensor
  • Damaged or defective climate control unit
  • An open or shorted circuit in the wiring harness between the climate control unit and evaporator temperature sensor

What are the symptoms of the B1946 code?

Symptoms of a B1946 code may include:

  • Check engine or warning light may illuminate
  • Climate control or A/C may not blow cold air
  • Climate control or A/C may not work at all
  • There may be no symptoms other than a stored B1946 code

How does a mechanic diagnose the B1946 code?

A mechanic may use several methods to diagnose a B1946 trouble code, including:

  • Utilize an OBD-II scanner to check for a stored B1946 trouble code
  • Visually inspect wiring and electrical components related to the evaporator temperature sensor for signs of damage
  • Visually inspect the evaporator temperature sensor for signs of damage
  • Test the resistance on the evaporator temperature sensor (resistance should be measured compared with temperature ranges)
  • Check the DATC sensor output voltage (it should be between 4.7 and 5.1 volts)
  • Disconnect climate control unit and evaporator temperature sensor connector and check for an open circuit that has less than 5 ohms resistance
  • Check return circuit for an open or short circuit
  • Check reference circuit for a short to ground
  • Check reference circuits for a short to the return circuits

How serious is the B1946 code?

Because a vehicle’s safe driving operation most likely will not be impacted due to faults that store a B1946 code, this code is not considered to be a serious code. When this code appears, it is recommended to take your vehicle to your local service center or mechanic for repair and diagnosis as soon as possible.

What repairs can fix the B1946 code?

Several repairs can fix a B1946 trouble code and include:

Additional information related to a B1946 code

It is always recommended to take all proper safety precautions when working with the electrical components of your vehicle and to carefully follow service instructions. With more complicated electrical repairs, it is recommended to seek assistance from a professional.

In addition, note that the evaporator core, driver side heater core, and passenger side heater core discharge air temperature sensors have the same diagnostic procedure.

Need help with a B1946 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.

trouble codes
OBD-II
B1946

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

SCHEDULE B1946 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

4.8/5

Number of Reviews

4,255

Rating Summary
3,898
174
45
26
112
3,898
174
45
26
112
Ben

Ben

39 years of experience
1020 reviews
Ben
39 years of experience
Lexus LS430 - Check Engine Light is on - Houston, Texas
I was very pleased with the courtesy and work of Mr. Smith. He was exceptional in explaining and correcting the problem and thereby gained my trustI . I request he be my mechanic in all future service requests. I had a great experience working with Mr. Ben Smith.
Richard

Richard

19 years of experience
203 reviews
Richard
19 years of experience
Ram ProMaster 1500 - Check Engine Light is on - Bonita Springs, Florida
Prompt, polite and personal. Took the time to explain the process and his recommendations. 2 thumbs up
Michael

Michael

23 years of experience
37 reviews
Michael
23 years of experience
Ford F-150 - Check Engine Light is on - Federal Way, Washington
Very helpful and explained everything and what needs to be addressed. I feel informed and confident in Mike’s assessment and look forward to him performing services on my vehicle.
Rigoberto

Rigoberto

9 years of experience
650 reviews
Rigoberto
9 years of experience
Honda Civic - Check Engine Light is on - Chicago, Illinois
Rigoberto came on time & quickly diagnosed the problem- rats chewed thru wiring near the battery. He wasn’t able to fix it himself bc of parts, but gave me recommendations on where to go & how to not have the dealership sell me services that are not needed.

More related articles

How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
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...

Related questions

Q: Intake maifold runner control is stuck open

Hello, thanks for writing in about your 2001 Mazda Miata. Due to this trouble code, the intake manifold runner control will need to be replaced. If this is not done you can cause serious damage to your car. If you...

Q: OBD-II scanner read code P0108

Hello. The MAP sensor reading on a scanner should read about 1.0 to 1.5 volts at idle and 4.5 to 4.8 volts at wide open throttle. The MAP should read 4.8 volts or more when you have the key on...

Q: Stutters under acceleration or load, fine at idle

If there are no codes for a random misfire on any cylinder, the ignition control module - what the ignition coils are plugged into - is known for causing your eact symptoms. It can cause intermittent misfires. I suggest having...

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