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U0140 on 2014-2018 Kia Forte: Lost Communication With Body Control Module Causes and Fixes

Q: My 2017 Kia Forte sometimes won't start unless I jump it, but the electronics seem fine. Could this be related to U0140?

Yes. An intermittent no-start condition that is resolved by a jump-start often points to a weak battery or poor connection. Since the BCM is sensitive to low voltage (below 12.4V), a failing battery is a primary cause for communication codes like U0140.

Q: Is there a TSB for steering issues on the 2014 Kia Forte that might be confused with electrical codes?

Yes, TSB CHA074 addresses a common failure of the MDPS (Motor Driven Power Steering) flexible coupling in the 2014 Forte (YD). While it causes clicking noises and steering play rather than U0140 codes, it is a known vehicle-specific issue.

Q: Could a problem with my brake lights cause starting issues on my 2013-2014 Forte?

Yes. Recall 15V015000 identifies a deteriorating brake light switch stopper pad. This can cause the brake lights to stay on and create potential starting issues, which may complicate the diagnosis of other electronic modules.

Q: I have a 2018 Forte; is there a recall that affects the electronic modules?

Yes, 2017-2018 models are subject to Recall 22V031000 / 21V260000 regarding the Airbag Control Unit (ACU). The ACU cover can contact a memory chip and damage it, potentially deactivating the airbags.

Q: Where is the Body Control Module located on the 2014-2018 Forte if I need to check the connectors?

The BCM is typically located behind the center console area or integrated as part of the interior fuse panel (Smart Junction Box).

Q: My 2015 Forte has a 1.8L engine and is consuming oil; could this trigger a U0140 code?

While the 1.8L and 2.0L Nu engines have widespread issues with oil consumption and failure (Recalls SC210 / 20V750), these are mechanical engine failures and are generally unrelated to the BCM communication loss indicated by U0140.

This code means the Body Control Module (BCM) has stopped communicating with other computers in the car. The most common causes are simple electrical issues like a weak battery, blown fuses, or a bad ground connection. Before suspecting a costly BCM failure, always check these basic items first.

20 minutes to read 2014-2018 Kia Forte

Most Likely Cause

Weak Battery or Poor Connections

Difficulty

4/5

Est. Time

2 hrs

DIY Doable?

🔧 Shop

Shop Labor

$150 – $800

Parts Price

$10 – $500

⚠️ Drivable, but... — Driving is possible but risky. You could experience a sudden failure of essential systems like headlights or wipers, or the anti-theft system could engage and prevent the car from starting at your next stop.

Key Takeaways

U0140 on a 2014-2018 Forte means the Body Control Module is offline.
Always start diagnostics with the easiest and most common causes: battery health, fuses, and ground connections.
Do not immediately assume the BCM has failed; it is more often a problem with the power or wiring going to it.
Driving with this code is not recommended, as safety-critical items like headlights and wipers can fail unexpectedly.
Due to the complexity of network diagnostics, professional service is highly recommended if the basic checks do not resolve the issue.

The trouble code U0140 stands for 'Lost Communication With Body Control Module (BCM)'. The BCM is a central computer that manages many of your car's non-engine electrical systems, including the power windows, door locks, interior and exterior lights, wipers, and the anti-theft immobilizer. When this code appears, it means that other essential modules, like the Engine Control Module (ECM), can no longer receive signals from the BCM over the vehicle's internal communication network, known as the CAN bus.

What's Unique About the 2014-2018 Kia Forte

The 2014-2018 Kia Forte (second generation, YD) does not have a widely documented, platform-specific pattern of failure that causes code U0140, unlike some other Kia models that have recalls for similar issues. The causes are typically rooted in general electrical and network principles rather than a known design flaw. The Body Control Module on this Forte is generally located behind the center console area or integrated into the driver-side interior fuse box (Smart Junction Box), which requires some interior trim removal to access for inspection.

Professional service recommended: Diagnosing network communication errors requires specialized tools like a multimeter and an advanced scan tool capable of communicating with all modules. Incorrectly testing wires can cause further damage to other modules on the network.

Symptoms You May Notice

Power windows, door locks, or mirrors stop working
Interior or exterior lights behave erratically or fail completely
Wipers do not function
Vehicle will not start, or only starts intermittently (crank-no-start)

🎬 See how to diagnose an intermittent no-start

Multiple warning lights illuminated on the dashboard (e.g., ABS, Traction Control, Airbag)
Key fob or keyless entry system is inoperative
Parasitic battery drain, causing a dead battery overnight

⚠️ Don't Waste Money on the Wrong Fix

Replacing the BCM without first verifying its power and ground connections. Many expensive modules are replaced when the actual fault was a simple blown fuse, a corroded ground wire, or a weak battery.

Most Likely Causes

Weak Battery or Poor Connections 🔴 High Probability → Shop Vehicle Battery All modern vehicles are sensitive to low voltage. A battery below 12.4 volts or with corroded terminals can easily cause communication modules to drop offline intermittently, triggering U-codes. 🎬 Watch: How to fix a U0140 code
How to confirm: Test the battery voltage with a multimeter. It should read at least 12.4V with the engine off and 13.7-14.7V while running. Ensure battery terminals are clean and tight. An intermittent no-start that is resolved by a jump-start often points to a battery or connection issue.
Typical fix: Charge or replace the battery. Clean the battery terminals and cable ends thoroughly.
Est. part cost: $150-$250
Blown BCM-Related Fuses 🟡 Medium Probability
How to confirm: Inspect all fuses in both the interior (driver's side dash) and engine bay fuse boxes. Check any fuses labeled 'BCM', 'Module', 'SJB' (Smart Junction Box), or 'Memory'.
Typical fix: Replace any blown fuses with new ones of the exact same amperage.
Est. part cost: $1-$10
Poor BCM Ground Connection 🟡 Medium Probability
How to confirm: Locate the BCM's main ground wire (typically a black wire bolted to the chassis). Use a multimeter to check for resistance between the ground pin on the BCM connector and a known good chassis ground. The reading should be less than 1 ohm. One common DIY fix involves adding a redundant ground wire.
Typical fix: Clean the ground point connection of any paint or corrosion and tighten the bolt securely.
Est. part cost: $0-$5
Damaged Wiring or Corroded Connector ⚪ Low Probability
How to confirm: Visually inspect the wiring harness leading to the BCM for any signs of chafing, cuts, or rodent damage. Disconnect the BCM connectors (with the battery disconnected) and check for any green or white corrosion on the pins.
Typical fix: Repair the damaged section of wire. Clean corroded connectors with an electrical contact cleaner and a small brush. Apply dielectric grease before reconnecting.
Est. part cost: $10-$100
Faulty Body Control Module (BCM) ⚪ Low Probability → Shop Body Control Module
How to confirm: This is confirmed by exclusion. If all power, ground, and CAN bus wiring to the module are verified to be good, but the module still does not communicate with a scan tool, the BCM itself has likely failed internally.
Typical fix: Replace the Body Control Module. The new module will require programming by a Kia dealership or a qualified shop with the appropriate software to match the vehicle's VIN and options.
Est. part cost: $200-$500

Rare But Worth Checking

Faulty Aftermarket Accessory: Poorly installed remote starters, alarms, or stereo systems that are tapped into the vehicle's CAN bus wiring can create electrical noise and disrupt communication, causing a U0140 code.
Another Failing Module on the Network: Rarely, a different module (like the ABS or instrument cluster) can fail in a way that it floods the CAN bus with bad data, preventing the BCM from communicating. This requires advanced diagnostics, such as unplugging modules one by one, to isolate the faulty component.
BCM Software Glitch: Occasionally, the BCM's internal software can become corrupted or have a bug that causes communication loss. Kia has issued TSBs for other models to update BCM/IBU software to fix various electrical issues, including anti-theft logic and remote start compatibility, indicating that software fixes are a known repair path.

Diagnosis Steps

Read All Fault Codes: Use a quality OBD-II scanner to check for any other 'U' codes that may be present. This can help determine if the communication loss is isolated to the BCM or is a network-wide problem.
Check Battery Health: Verify the battery has a static charge of at least 12.4 volts and that the terminals are clean and tight. A weak battery is a very common cause.
Inspect All Fuses: Carefully check all fuses related to the BCM, body electronics, and modules in both the interior and engine compartment fuse panels. Pay attention to fuses labeled 'BCM', 'Module', and 'Memory'.
Inspect BCM and Connectors: Disconnect the battery. Access the BCM (located behind the center console area or as part of the interior fuse panel) and visually inspect its connectors for corrosion, moisture, or loose pins.
Verify BCM Power and Ground: Reconnect the battery. With the ignition on, use a multimeter to test the power supply pins at the BCM connector (should show battery voltage) and the ground pins (should show less than 1 ohm of resistance to the chassis).
Check CAN Bus Resistance: Disconnect the battery again. At the OBD-II port, measure the resistance between Pin 6 (CAN High) and Pin 14 (CAN Low). A healthy network should read approximately 60 ohms. A reading of 120 ohms suggests a break in the wiring or a missing termination resistor, while a reading near 0 ohms indicates a short circuit.
Isolate the Module: If all wiring, power, and grounds are confirmed to be good, and a professional scan tool cannot communicate with the BCM, the module itself is the most likely point of failure.

Parts You'll Likely Need

Body Control Module (BCM) (OEM #95400-A7100, 95400-A7640, 95400-A7630) — If all power, ground, and network wiring tests pass, the internal circuitry of the BCM is the likely cause of the communication loss. Part number varies by features like keyless entry, central locking, etc.
Trusted brands: Kia (OEM)
OEM price range: $300-$500
Aftermarket price range: $200-$400

Related Codes That Often Appear With This One

U0100 — Lost Communication with ECM/PCM. This and other U-codes often appear alongside U0140, indicating a wider network communication problem.
U0155 — Lost Communication With Instrument Panel Cluster Control Module. The instrument cluster is another key module on the CAN bus, and network-wide issues will often cause multiple communication codes.
U0073 — Control Module Communication Bus 'A' Off. This code points directly to a general failure on the primary CAN bus, which would explain why the BCM cannot communicate.

Technical Service Bulletins (TSBs) & Recalls

TSB CHA074: Details the replacement procedure for the MDPS (Motor Driven Power Steering) flexible coupling, a common failure on the 2014 Forte (YD) that causes steering noise and play.

Mechanic-Grade Diagnostic Values

CAN Bus Network Resistance — expected: Approximately 60 Ω. Failure: A reading of 120 Ω indicates an open circuit or a missing terminating resistor. A reading near 0 Ω indicates a short between the CAN High and CAN Low wires. A reading of ~40 Ω may indicate a third, improper terminating resistor on the network.
CAN Bus Voltage to Ground — expected: CAN High (Pin 6): ~2.6V. CAN Low (Pin 14): ~2.4V.. Failure: Voltages that are the same (e.g., both 2.5V) can indicate a short between the wires. Voltages at 0V can indicate a short to ground.
BCM Ground Circuit Resistance — expected: Less than 1.0 Ω (ideally < 0.1 Ω). Failure: A reading higher than 1.0 Ω indicates a poor ground connection, which can cause module communication issues.
BCM Operating Voltage — expected: 9V to 16V. Failure: A voltage supply below 9V can cause the module to shut down or behave erratically.

Scan Tool Commands That Help

Kia GDS (Global Diagnostic System): BCM Diagnosis / Actuation Test — To verify if the GDS can communicate with the BCM and to command specific outputs (like lights, locks) to test the BCM's functionality directly.
Kia GDS (Global Diagnostic System): Transmitter Code Registration — This function is mandatory after replacing the BCM to program the existing key fobs to the new module. Without this step, the keyless entry and possibly the immobilizer will not work.
Kia GDS (Global Diagnostic System): Vehicle S/W Management — Used for special functions like writing the VIN to a new module or resetting adaptive values. This may be required depending on the specific replacement BCM used.

Wiring & Ground Locations

Body Control Module (BCM) — Located behind the center console area, accessible after removing the heater/AC control unit and the center lower cover.. This is the module that has lost communication. Physical access is required to test its power, ground, and network connections, and to inspect for corrosion or damage.
Data Link Connector (DLC) — Under the driver's side dashboard, standard 16-pin OBD-II port.. This is the primary non-invasive test point for the entire CAN network. Pin 6 (CAN-H) and Pin 14 (CAN-L) are used to measure network resistance and voltage.
BCM Ground Point — Bolted to the metal chassis structure in the vicinity of the BCM, behind the center console.. A loose or corroded ground is a high-probability cause for communication loss. Verifying this connection has less than 1 ohm of resistance to the chassis is a critical diagnostic step.

OEM Part Supersession History

95400A7xxx (e.g., 95400A7640, 95400A7DH0) → Varies — Applies to pre-facelift models.
Heads up: These parts are for the 2014-2016 Forte. They are likely incompatible with 2017-2018 models which use different part number series.
95400Bxxxx (e.g., 95400-B0221, 95400-B0720) → Varies — Applies to post-facelift models.
Heads up: These parts are for the 2017-2018 Forte. They are likely incompatible with 2014-2016 models. Part number must be matched exactly to the original unit.

Model Year Variations Within This Range

2014-2016 vs 2017-2018: The Body Control Module part numbers are different for the pre-facelift (2014-2016) and post-facelift (2017-2018) models. For example, early models use 95400-A7xxx series part numbers, while later models use 95400-Bxxxx series. The modules are not interchangeable, and the exact part number from the original unit must be used for replacement.

Diagnostic Flowchart

U0140 indicates a loss of communication with the Body Control Module (BCM). Because the 2014-2018 Forte (YD) platform is highly sensitive to voltage drops, start by verifying the electrical foundation before condemning the BCM.

Measure battery voltage with the engine off. Is it at least 12.4V, and are terminals free of corrosion?

→ Charge or replace the battery and clean terminals. Low voltage is the #1 cause of communication codes on the Forte and its platform-mate, the Hyundai Elantra (MD).

Inspect the interior driver-side dash fuse box and engine bay box. Are fuses labeled 'BCM', 'SJB', or 'Memory' intact?

→ Replace with the exact amperage fuse. If it blows again, inspect the wiring harness for shorts, especially near the door hinges or trunk.

Locate the BCM ground (black wire to chassis). Is resistance between the BCM ground pin and a clean chassis point less than 1 ohm?

→ Clean the ground point of paint and corrosion. For 2014-2018 models, adding a redundant ground wire to the chassis is a common DIY fix to stabilize the BCM.

Disconnect the battery and unplug the BCM (behind the center console/junction box). Do you see green/white corrosion or moisture?

→ Clean pins with electrical contact cleaner, apply dielectric grease, and check for cabin water leaks that may be dripping onto the Smart Junction Box.

With the battery disconnected, measure resistance between OBD-II Pin 6 and Pin 14. Is it approximately 60 ohms?

→ There is a break or short in the CAN High/Low wiring. Trace the twisted pair wiring between the OBD-II port and the BCM for damage.

If power, ground, and CAN bus signals are verified but the BCM remains unresponsive to a professional scan tool, the module has failed.

→ Replace the Body Control Module. Note: On 2014-2018 Fortes, the new BCM must be programmed by a dealer or locksmith to match your VIN and key fob settings.