B2108 OBD-II Trouble Code: Trunk Key Cylinder Switch Failure

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

SCHEDULE B2108 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the B2108 code

B2108 is a diagnostic trouble code (DTC) for "Trunk Key Cylinder Switch 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. 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$20.00
Toyota$20.00
BMW$20.00
SCHEDULE B2108 DIAGNOSTIC Get a fair and transparent estimate upfront

B2108 code definition

The B2108 trouble code detects a trunk key cylinder switch failure.

What the B2108 code means

The B2108 code is a generic OBD-II body trouble code that notes a trunk key cylinder switch failure. The key cylinder switch is located in the trunk door, and allows the trunk to be manually locked or unlocked using the key. When the key is inserted into the trunk lock (located directly next to the trunk handle), and rotated, then the cylinder switch causes the trunk to lock or unlock. If at any point the trunk key cylinder switch is failing to lock or unlock the vehicle, then the body control module will most likely store the B2108 trouble code.

What causes the B2108 code?

The only common cause of the B2108 trouble code is a defective trunk key cylinder switch. There are a few different components in the cylinder switch that may fail, but regardless of what part is defective, the entire cylinder switch will need to be replaced. In very rare cases, the code may be the result of a malfunctioning body control module.

What are the symptoms of the B2108 code?

If the B2108 trouble code is detected, then the trunk likely will not be able to be manually locked or unlocked using the key. It is also possible that the check engine soon Warning Light will illuminate on the gauge cluster.

How does a mechanic diagnose the B2108 code?

An inspection of this code should begin by using a standard OBD-II trouble code scanner. It might seem unnecessary to use a scanner for this issue, which can be easily verified, but a scanner allows the mechanic to assess the body control module, and also to see if there are any additional trouble codes detected. If numerous trouble codes are present, then the mechanic will diagnose them in the order that they appear in. The codes will then be reset, the vehicle restarted, and the B2108 code checked for. If the code has gone away, and the exterior trunk manual lock is functioning properly, then the code was most likely detected erroneously, or is the result of an intermittent error.

If the code remains detected, then the trunk key cylinder switch should be replaced. Once the cylinder switch has been replaced, the trouble codes should again be reset, the vehicle again restarted, and the B2108 code checked for again. If the code remains present, then the body control module has most likely failed.

Common mistakes when diagnosing the B2108 code

The most commonly made error when diagnosing this code comes from a failure to properly abide by the OBD-II trouble code diagnosis protocol. The protocol should always be observed step by step, as this helps ensure thorough and accurate diagnoses.

It is fairly common for the trunk key cylinder switch to be replaced without an OBD-II trouble code scanner being used to check the codes. If this mistake is made, other problems that are present in the vehicle will not be noticed.

How serious is the B2108 code?

The B2108 code will not keep a car from being drivable, or cause drivability concerns. However, the trunk will likely not be able to be manually locked or unlocked with the key, which may cause security or practicality problems. While the B2108 code is not urgent, an inspection should be scheduled when the code is detected.

What repairs can fix the B2108 code?

The B2108 code will almost always be resolved by replacing the trunk key cylinder switch. In very rare cases, the body control module might require replacement.

Additional comments for consideration regarding the B2108 code

The B2108 code is a manufacturer specific code, which means that the definition can vary from automaker to automaker. While this code detects a trunk key cylinder switch failure in some vehicles, it may signal a much different body failure in other cars. The mechanic should always pay attention to the vehicle that is being worked on when diagnosing the B2108 code.

Need help with a B2108 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
Check Engine Light
Trunks
B2108

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

SCHEDULE B2108 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

4,743

Rating Summary
4,361
185
47
28
122
4,361
185
47
28
122

Oreste

12 years of experience
108 reviews
Oreste
12 years of experience
Nissan Altima - Check Engine Light is on - Hialeah, Florida
Showed up quick, and went straight to inspecting a brake light on the dash issue. He found the issue, fixed it, and showed me exactly what was wrong. Thank you!

Daniel

9 years of experience
58 reviews
Daniel
9 years of experience
Honda Fit - Check Engine Light is on - Chicago, Illinois
Told me everything I needed to know and switch out after the inspection. So, I scheduled another service the next day for all the fixes, or fluid maintenance.

Patrick

31 years of experience
1032 reviews
Patrick
31 years of experience
Hyundai Santa Fe - Check Engine Light is on - Austin, Texas
Even after working on my car, he took the time to explain what he did, the parts, and any next steps. Very knowledgeable!

Joe

12 years of experience
22 reviews
Joe
12 years of experience
Toyota 4Runner - Check Engine Light is on - Sacramento, California
Joe was very thorough in his inspections, and his knowledge & experience was clear in his explanations of what was wrong with my car. I really appreciated his recommendations, and the fact that he worked so efficiently that it cut down on time... I would definitely book with him again.

More related articles

How to Transfer a Car Title in Idaho
In In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs to be transferred into the new owner’s name. The state of Idaho has...
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. You may want to check out the Ethnology Museum, or the Southern...
What are the Car Pool Rules in Hawaii?
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 states, freeways are an integral part of life...

Related questions

Can shaft position sensor all of the outcomes of the problem

Possibilities: 1 - Simply replacing the camshaft sensor will solve your problem. 2 - If it does not, with the age of the vehicle, there can be a break in the wiring harness to the cam sensor. 3 - If...

the car has suffocation feeling when accelerator is pressed and does not speed constantly

This sounds like a low fuel pressure problem, or an air filter and mass airflow (MAF) sensor problem. Check the fuel pressure and replace the fuel filter first to see if it helps. Next, have the system computer scanned...

What does the liftgate ajar Warning Light mean?

The liftgate ajar Warning Light is located on the instrument panel. This light illuminates when your trunk is not properly closed. Secure your trunk properly, and the light will turn off.

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