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  • A problem with the 4WD switch circuit will cause the powertrain control module to log a P0837 trouble code.
  • 4WD switch failure, wiring problems, and issues with the transfer case module can trigger a P0837 code.
  • If left unaddressed, this code can cause your vehicle to exhibit symptoms like a flashing 4WD drive light and deactivated 4WD mode.

Vehicles with a four-wheel drive (4WD) system have a transfer case that acts as an auxiliary two-speed transmission, directing engine torque to both front and rear axle assemblies. A 4WD switch circuit is needed to select a mode or configuration that affects the transfer case gear ratios. If the transmission control module (TCM) is unable to detect a signal from the 4WD switch circuit, a P0837 code will be set.

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What Does the P0837 Code Mean?

Diagnostic trouble code (DTC) P0837 stands for “Four-Wheel DRIVE (4WD) Switch Circuit Range/Performance.”

The 4WD switch circuit informs the TCM what mode the system is in (two-wheel high, two-wheel low, neutral, four-wheel high, and four-wheel low).

transfer case for car
The transfer case lets the driver select a low-speed, high-power gear ratio while in 4WD mode.

The transfer case lets the driver select a low-speed, high-power gear ratio while in 4WD mode. For a configuration to kick in, the drive axles must be connected. This lets the torque from the front differential flow to the drive wheels.

A problem detected with the 4WD switch circuit will prompt the powertrain control module (PCM) to log a P0837 trouble code.

Note: The definition of code P0837 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P0837 Code?

  • 4WD switch failure
  • Wiring issues
  • Transfer case module problems

What are the Common Symptoms of the P0837 Code?

  • Flashing 4WD drive light
  • Deactivated 4WD mode
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How to Diagnose the P0837 Code

DTC P0837 is a generic powertrain code that can be logged in 4WD vehicles with an OBD-II system. However, keep in mind that the steps for diagnosis and repair can vary, depending on vehicle specifications.

Diagnosing a P0837 might require you to use certain tools and conduct inspections, which can be tricky if you’re not familiar with the entire process. Luckily, you can always have a certified mechanic do the job for you.

How to Fix the P0837 Code

Without the right tools and technical information, attempting to fix a DTC P0837 can be frustrating and confusing. If done incorrectly, it can even lead to further complications. Under these circumstances, it’s best to have the problem fixed by a trained professional to ensure that all steps and protocols are followed properly.

But if you think you can handle the problem on your own, make sure you have the right information before proceeding. Keep in mind that there’s no such thing as a magic bullet that will work on all makes and models. So before you begin, you might want to check out guides like those from Chilton or an ALLDATA subscription to get vehicle-specific repair information.

About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Contact Center Manager and Technical Reviewer at

William “Bill” Guzenski has produced hundreds of how-to videos for the automotive community. He’s an ASE Certified Master Automobile Technician, and is affiliated with the Specialty Equipment Market Association (SEMA). He loves attending race events and car shows throughout the country, as well as traveling in his 40-foot motorhome, exploring abandoned mines and ghost towns.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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