By iCarsoft Official Store Technical Team, Automotive Diagnostics Editors · Updated October 14, 2026 · Technical sources checked
Quick Answer
U012B is the bounded JLR 2013MY L405 record for lost CAN communication with optional CHCMB after battery disconnection. Confirm CHCMB fitment and model year; a reset is not proof of suspension readiness.
What Does the U012B Code Mean?
JLR SSM69398 is a 2013MY Range Rover L405 application. Receivers of CAN messages from optional CHCMB may log U012B-00 after battery supply disconnection because the chassis control module B may not power up correctly. The full fault record determines the test branch.
JLR SSM69398 documents U012B-00 on 2013MY Range Rover L405 when receivers lose CAN messages from optional CHCMB after battery supply disconnection. The notice distinguishes 2014MY L405/L494, which may use U0001-87. Confirm that CHCMB is fitted and that the vehicle is within the cited application before using any recovery step. A useful comparison is the receiver’s behavior before and after the approved wake sequence.
If several receivers lose CHCMB at the same time, shared supply or network evidence deserves priority over an isolated module conclusion. If only one receiver reports the code while the JLR tool can access CHCMB, preserve the event as historical or intermittent and look for companion status rather than replacing hardware. The optional CHCMB qualification is especially important because a non-installed module cannot be diagnosed as a failed physical unit.
Any battery-related action must follow the vehicle procedure and must not be converted into a universal timed reset. Ask which receiver stored the record and whether it was current, pending or historical. Those fields change the meaning of a message timeout. A module that responds on a second scan is evidence against a continuously failed controller, but it does not rule out an intermittent wake or connector issue.
Conversely, an unreachable CHCMB does not by itself prove CHCMB internal failure because shared power and network conditions must be proven first.
JLR SSM69398 is a 2013MY Range Rover L405 application. Receivers of CAN messages from optional CHCMB may log U012B-00 after battery supply disconnection because the chassis control module B may not power up correctly.
JLR SSM69398 — CHCM/CHCMB communication after battery reconnection identifies U012B as Lost Communication with Chassis Control Module B in a bounded vehicle or module context. The source supplies terminology and limited mechanism evidence; it does not provide a universal topology, threshold or replacement instruction. JLR SSM69398 is a 2013MY Range Rover L405 application. Receivers of CAN messages from optional CHCMB may log U012B-00 after battery supply disconnection because the chassis control module B may not power up correctly.
2013MY Range Rover L405 only in the cited notice; CHCMB is optional and 2014MY L405/L494 may use U0001-87 instead. The cited suspension warnings are functional warnings; a reset or restored scan session does not prove adaptive-dynamics or ride-height readiness.
Save the full module wording and suffix before clearing; they can change the test path.
Separate U012B from adjacent fault families
| Code | General description | Key distinction |
|---|---|---|
| U012B | Lost Communication with Chassis Control Module B | This guide concerns the named controller message path. |
| U0073 | Control Module Communication Bus A Off | A bus-off result is a different network condition; confirm the actual fault record. |
| U0140 | Lost Communication with Body Control Module | A body-network code is not interchangeable with this module-specific result. |
Record the complete U012B description. The suffix, reporting module and companion faults can change the diagnostic path. Use the manufacturer's full wording and test procedure for the exact vehicle.
U012B Symptoms and Likely Causes
Record U012B symptoms and fault status; symptoms alone cannot identify a failed part.
Check whether companion faults share a proven cause.
Record the exact warning, when it appeared and which function changed; it is evidence, not proof of a failed controller.
Compare saved multi-module reports with supported live data; unavailable data does not identify the cause.
Preserve service history and inspect the disturbed branch first while treating timing as a clue.
Save every module's codes and status; a shared supply or network code can change the diagnostic order.
Practical cause-checking order
- Optional CHCMB not waking after the documented battery-supply interruption: Optional CHCMB not waking after the documented battery-supply interruption
- Receiver-side CAN path or CHCMB connector issue: Receiver-side CAN path or CHCMB connector issue
- Shared chassis-module supply, ground or gateway condition: Shared chassis-module supply, ground or gateway condition
- CHCMB absent or configuration not matching the scan expectation: CHCMB absent or configuration not matching the scan expectation
- Internal CHCMB fault only after external evidence passes: Internal CHCMB fault only after external evidence passes
Did U012B appear after recent battery reconnection, chassis-control or harness work? Recheck the documented connections, parts and setup steps affected by that work. Record battery and software history; a post-repair code does not prove the new part is defective.
How Serious Is U012B, and Can You Drive?
The cited suspension warnings are functional warnings; a reset or restored scan session does not prove adaptive-dynamics or ride-height readiness. Follow the owner manual and all vehicle warnings. U012B does not establish a safe remaining driving distance. Stop safely and arrange qualified inspection or towing for abnormal function; do not use a successful scan as permission to bypass a warning.
Record warning messages, operating conditions and service history. Do not induce wheel slip, emergency braking or a handling event on public roads. A red stop warning or abnormal control overrides any verification plan.
Stop and arrange a tow if steering, braking, propulsion, charging, parking-brake or other safety behavior is abnormal.
Follow the vehicle-specific electrical, steering, suspension or driveline safety precautions. Do not bypass interlocks or command powered safety components outside the approved procedure.
How to Diagnose U012B in the Right Order
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Identify the application and preserve evidence
Save the reporting modules, U012B status and all suspension/adaptive-dynamics warnings.
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Inspect the relevant physical and electrical path
Confirm the 2013MY L405 application and whether CHCMB is actually fitted; do not assume the B module exists.
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Confirm architecture and prerequisites
Record battery reconnection history and separate this application from the 2014MY L405/L494 U0001-87 scenario.
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Separate network behavior from system behavior
Inspect the approved low-voltage feed, connector and wake path for CHCMB under JLR service conditions.
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Prove the repair path before parts
Confirm the module is visible to the SDD tool and distinguish a power-up strategy condition from a persistent CAN fault.
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Verify the original condition after repair
Complete the prescribed suspension/adaptive-dynamics functional verification after communication returns.
Specifications are vehicle-specific. Use the exact VIN specifications, approved test points and required operating state. No generic value or drive cycle can replace the applicable procedure. Manufacturer examples here do not establish specifications for other applications.
U012B Repairs and Cost Planning
A U012B repair must address the demonstrated failure. Do not replace an assembly from the code alone.
Recheck installation and required setup after repair. 2013MY Range Rover L405 only in the cited notice; CHCMB is optional and 2014MY L405/L494 may use U0001-87 instead.
Ask the shop to name the failed branch and the measurement supporting each proposed repair.
Authorize diagnosis before parts while the cause remains uncertain.
| Possible path | Quote basis |
|---|---|
| Repair the demonstrated power, ground, connector, harness, gateway or network branch | VIN-specific quote |
| Restore configuration, software or required setup only through the VIN-specific procedure | VIN-specific quote |
| Replace the isolated controller or assembly only after external evidence and the OEM test support that path | VIN-specific quote |
These are alternative repair paths, not prices to add together. Request a VIN-specific quote separating diagnosis, parts, labor, fluids, taxes, required setup and verification. Ask which failed test supports the proposed repair and whether warranty coverage applies.
Using iCarsoft CR Pro S for U012B
On a supported vehicle, iCarsoft CR Pro S can save accessible faults, available freeze frame, live data and diagnostic reports. Preserve the U012B evidence before clearing.
Compare the saved and final module records. Scan data supports diagnosis but does not replace the OEM reference, physical measurement or safety-system functional check.
Preserve the chassis-control module B power, ground, wake and CAN path evidence
iCarsoft CR Pro S
Review supported codes and relevant live data together. Confirm the exact VIN, controller access, PIDs and any requested active test with iCarsoft before purchase; generic product capabilities do not guarantee a U012B-specific function.
Check current CR Pro S price and availabilityCheck CR Pro S compatibility by VINThe official product page describes supported full-system diagnostics, available live data, freeze frame and diagnostic reports; exact controller coverage and active tests depend on the VIN and software. Confirm the requested function by VIN before purchase. Follow OEM prerequisites and stop for abnormal operation.
Know the measurement boundary. Scan data describes ECU-provided information; it does not directly prove the physical condition of the chassis-control module B power, ground, wake and CAN path. Where required, use approved multi-module scan access, wiring diagram, voltage-drop/continuity tools and the VIN-specific network procedure and compare reported values with the relevant measured evidence.
Verify the U012B Repair
After repair, verify installation, clearance and required setup. Save the final findings and clear only erasable records as instructed. Battery disconnection is not a repair.
Run the manufacturer's applicable verification conditions in a safe workshop or route. Compare the original operating state with current data for the chassis-control module B power, ground, wake and CAN path, and check current and pending faults in related modules. A clean start or idle period does not prove the repair; use the OEM functional check for the affected system.
Compare the original and final fault status. Record the functional-check result and whether the original event returned.
If U012B returns, compare its suffix, status, failure order and operating conditions with the saved baseline before replacing another part. Revisit the failed branch and inspect anything disturbed. Confirm the prescribed affected-system functional verification separately from code clearing.
Verification follows the system involved. After saving the original evidence, use the OEM procedure to clear erasable records, complete any required calibration or functional check, and compare the final module status with the original warning and fault conditions.
Related Chassis-Control Module B Power, Ground, Wake And CAN Path Code Guides
Compare the related monitor families below. Shared symptoms or components do not make their repair procedures interchangeable.
U012B Frequently Asked Questions
Does U012B prove the Chassis Control Module B is bad?
No. JLR SSM69398 is a 2013MY Range Rover L405 application. Receivers of CAN messages from optional CHCMB may log U012B-00 after battery supply disconnection because the chassis control module B may not power up correctly. Use the VIN-specific procedure to prove the responsible feed, connector, network branch or controller before replacing parts.
What should I check first for U012B?
Save every module's codes and freeze frame before clearing. Confirm the full definition, suffix and VIN architecture. Then inspect recent battery reconnection, chassis-control or harness work, connectors and shared supplies. Those facts determine whether the next test needs approved multi-module scan access, wiring diagram, voltage-drop/continuity tools and the VIN-specific network procedure or a manufacturer-specific functional procedure.
Can I drive with the U012B code?
The cited suspension warnings are functional warnings; a reset or restored scan session does not prove adaptive-dynamics or ride-height readiness. Follow the owner manual and all vehicle warnings. U012B does not establish a safe remaining driving distance. Stop safely and arrange qualified inspection or towing for abnormal function; do not use a successful scan as permission to bypass a warning.
Why did U012B return after a part was replaced?
The cited suspension warnings are functional warnings; a reset or restored scan session does not prove adaptive-dynamics or ride-height readiness.
What should a U012B repair estimate include?
Ask for the failed-test evidence and a VIN-specific breakdown of diagnosis, parts, labor, taxes, required setup and verification. A code alone cannot establish the repair price.
Can CR Pro S diagnose and clear U012B?
On a supported vehicle, CR Pro S can organize available faults, freeze frame, live data and reports, and can clear erasable records after repair. Confirm exact ECU coverage. It cannot replace the OEM functional procedure or physical measurements for the chassis-control module B power, ground, wake and CAN path.
The iCarsoft Official Store Technical Team maintains the store's fault-code library. This guide organizes published technical references and verified product information; it does not document a hands-on test of a particular vehicle or claim an individual engineer's review.
Technical and cost references
- JLR SSM69398 — CHCM/CHCMB communication after battery reconnection. Primary-source terminology and bounded mechanism evidence; not a universal repair criterion.
- Subaru Electrical Systems Operation & Diagnosis Module 602. OEM training context for no-message communication faults; it does not set another vehicle’s topology or thresholds.
Product information: Official iCarsoft CR Pro S page.
Editorial note: General diagnostic education, not a substitute for the owner's manual, current VIN-specific service information or professional inspection. Test limits, procedures, coverage and costs vary. Related articles provide context; apply only the specifications and repair procedures that match the vehicle. No universal failure rate, repair price or outcome is implied.
