U0167 – Lost Communication With Vehicle Immobilizer Control Module

System: Network | Standard: ISO/SAE Controlled | Fault type: General

Definition source: SAE J2012/J2012DA (industry standard)

DTC U0167 indicates that one or more control modules on the vehicle network have detected a loss of communication with the Vehicle Immobilizer Control Module. Because this is a network communication fault, it does not by itself prove that the immobilizer module has failed; it only confirms that expected data messages were not received within a required time window. The exact enabling conditions, timeouts, and which modules set the code can vary by vehicle platform and configuration, so verify the monitor description, network topology, connector views, and test points in the applicable service information before deep diagnostics. Treat U0167 as a system-level communication problem until power, ground, and network integrity are confirmed.

What Does U0167 Mean?

U0167 – Lost Communication With Vehicle Immobilizer Control Module means the vehicle’s networked control system detected that communication with the immobilizer control module was lost. Under SAE J2012 DTC structure, a U-code is a network-related diagnostic trouble code set when modules cannot exchange required messages over the vehicle communication bus. In practical terms, at least one module expected to receive immobilizer-related data (such as authorization or status) did not receive it as required, so it flagged a loss-of-communication condition and stored U0167.

Quick Reference

  • Subsystem: Vehicle network communication between control modules and the Vehicle Immobilizer Control Module
  • Common triggers: Immobilizer module offline, loss of module power/ground, open/short on network wiring, poor connector contact, network faults affecting message traffic
  • Likely root-cause buckets: Wiring/connector faults; power/ground issues; network bus integrity issues; module internal fault; configuration/software issues (varies by vehicle)
  • Severity: Often high; may cause no-start, start-and-stall, or security-related inhibit depending on vehicle strategy
  • First checks: Scan for additional U-codes; verify immobilizer module presence on the network; check related fuses/feeds/grounds; inspect connectors for looseness/corrosion; verify battery condition
  • Common mistakes: Replacing keys/modules first; ignoring shared power/ground or splice points; overlooking low system voltage or a network wiring fault upstream

Theory of Operation

The vehicle immobilizer control module participates on the vehicle communication network and exchanges security authorization and status messages with other modules. Depending on design, the immobilizer module may validate a key transponder, coordinate with another security component, and provide an enable/authorization message that allows starting and continued operation. Other modules monitor for these messages as part of their normal operating logic.

U0167 sets when a receiving module determines that immobilizer-related messages are missing, invalid, or not updating within the expected interval. This can occur if the immobilizer module loses power or ground, the module is disconnected, the network wiring has an open/short or excessive resistance, or the network is disrupted by another fault. Because the monitor is communication-based, diagnosis focuses on network presence, wiring integrity, and stable module power/ground rather than sensor signal calibration.

Symptoms

  • No-start: Engine may crank but not start if authorization is not received
  • Start-then-stall: Engine may start briefly and then shut down as authorization is lost
  • Security indicator: Security/immobilizer warning lamp may illuminate or flash (varies by vehicle)
  • Intermittent starting: Starts normally at times, then fails due to intermittent communication
  • Multiple U-codes: Additional network communication codes may be stored in several modules
  • Reduced functionality: Convenience or network-dependent features may be limited if the network is unstable

Common Causes

  • Open circuit, high resistance, or intermittent connection in the network communication wiring between modules
  • Poor terminal fit, corrosion, bent pins, or partially seated connectors at the immobilizer control module or at network splice/junction points
  • Power feed issue to the vehicle immobilizer control module (blown fuse, faulty relay, or open in the module B+ supply circuit)
  • Ground circuit problem for the vehicle immobilizer control module (loose ground fastener, corrosion, damaged ground wire, or excessive voltage drop)
  • Network wiring shorted to ground or shorted to power, disrupting communication on the bus
  • Internal fault within the vehicle immobilizer control module (communication interface failure)
  • Fault in another module on the same network that loads the bus and prevents normal messaging (varies by vehicle network topology)
  • Low system voltage or unstable electrical supply during cranking/start events causing modules to reset and drop off the network

Diagnosis Steps

Tools that help: a scan tool that can read network DTCs across all modules and display module status, a digital multimeter for power/ground and voltage-drop testing, wiring diagrams and connector pinouts from service information, and basic back-probing/terminal inspection tools. If available, a lab scope can help assess network integrity, but many faults can be isolated with scan data and careful circuit checks.

  1. Confirm U0167 is present and record freeze-frame/environment data if available. Then run a full network scan and save the report so you can see which modules are offline and which network-related DTCs are stored.
  2. Check whether the scan tool can communicate directly with the vehicle immobilizer control module. If it is completely non-communicative, prioritize module power/ground and network wiring checks before considering module replacement.
  3. Look for obvious conditions that can disrupt communication: low battery state, loose battery terminals, recent jump-start events, or aftermarket electrical add-ons. Correct any basic power supply issues first, then recheck for DTC return.
  4. Using service information, identify the immobilizer control module power feeds, ignition feeds (if applicable), and grounds. Verify related fuses and relays under load (not just visually). If a fuse is blown, investigate for shorts before replacing it.
  5. Perform voltage-drop testing on the immobilizer module ground circuit(s) while the circuit is loaded (key on, and if applicable during crank). Excessive drop indicates resistance in the ground path that can cause module resets or communication loss.
  6. Check the immobilizer module B+ and ignition feed circuits at the connector with the module connected (back-probe if possible). Look for evidence of intermittent supply loss (for example, supply dropping out when harnesses are moved). Compare findings to service information expectations.
  7. Inspect the immobilizer module connector and nearby harness routing. Look for pushed-out pins, fretting, corrosion, moisture intrusion, damaged insulation, or previous repairs. Repair terminal tension issues and correct any poor pin fit.
  8. Verify network circuit integrity between the immobilizer module and the network backbone/splice points (varies by vehicle). With the system powered down as required by service information, check for opens and shorts in the network wiring using continuity and isolation checks. Do not assume a single wire color or pinout without diagrams.
  9. Perform a wiggle test: while monitoring scan tool live data (module online/offline status, communication counters if available) gently move the immobilizer harness, connector, and nearby network splice areas. If communication drops in and out, focus on that section for an intermittent open/high resistance or terminal issue.
  10. If the immobilizer module has confirmed good power and grounds and the network wiring tests good, use the scan tool to observe whether other modules report bus-off or communication errors at the same time. A different module or wiring fault may be loading the network; isolate by inspecting shared splices and any recently serviced areas.
  11. After repairs, clear DTCs and perform an operational check appropriate to the system (key cycle, start attempt, and a short drive if permitted). Re-scan the network and confirm U0167 does not return and that the immobilizer module remains consistently communicative.

Professional tip: Log scan tool data (module presence/online status and network-related DTCs) during the exact conditions when the fault occurs, especially during crank or immediately after key-on. Many U0167 cases are intermittent power/ground drops or terminal fretting that only show up with vibration or high electrical load, and a captured “module went offline” event can point you to the correct circuit to voltage-drop test.

Need network wiring diagrams and module connector views?

Communication stop and network faults require module connector pinouts, bus wiring routes, and power/ground diagrams. A repair manual helps you trace the exact circuit path before replacing any ECU.

Factory repair manual access for U0167

Check repair manual access

Possible Fixes & Repair Costs

Repair cost and effort can vary widely because U0167 is a network communication fault. The final scope depends on whether the issue is a simple connection/power problem or requires deeper network testing and module configuration after verified diagnosis.

  • Restore power and ground to the vehicle immobilizer control module after confirming loss with testing
  • Clean, tighten, or repair module and network connectors (terminal tension, corrosion, moisture intrusion, pin fit)
  • Repair or replace damaged network wiring (open, short, or high resistance) based on continuity and voltage-drop results
  • Correct network faults affecting multiple modules (backed-out terminals, harness chafing, poor splices) once isolated
  • Replace the vehicle immobilizer control module only after all power/ground/network checks pass and communication remains absent
  • Perform required setup, configuration, or security initialization steps that vary by vehicle after verified module replacement

Can I Still Drive With U0167?

Driving with U0167 is not recommended until you understand the symptom severity on your vehicle. Lost communication with the vehicle immobilizer control module can lead to a no-start, intermittent start-and-stall, or security-related inhibiting of engine operation. If the vehicle exhibits stalling, no-start, repeated warning indicators, or unpredictable behavior, do not drive it—have it diagnosed and repaired. If it starts and runs normally, drive only as needed and avoid shutting the engine off until you reach a safe location for service, since restart may fail.

What Happens If You Ignore U0167?

Ignoring U0167 can leave you with an intermittent or sudden no-start condition and increased risk of being stranded. Communication faults can also mask other network issues, create additional communication DTCs, and complicate future diagnosis. Over time, the underlying cause (such as a loose connector, poor ground, or harness damage) may worsen, making the fault more frequent and harder to reproduce.

Compare nearby lost vehicle trouble codes with similar definitions, fault patterns, and diagnostic paths.

  • U0168 – Lost Communication With Vehicle Security Control Module
  • U017D – Lost Communication With Control Module “M”
  • U017C – Lost Communication With Control Module “L”
  • U017B – Lost Communication With Control Module “K”
  • U017A – Lost Communication With Control Module “J”
  • U0179 – Lost Communication With Control Module “I”

Key Takeaways

  • U0167 indicates lost communication with the vehicle immobilizer control module, not a confirmed hardware failure by itself
  • Most successful fixes start with power, ground, connector integrity, and network wiring checks before replacing modules
  • Intermittent faults are common; live-data logging and wiggle testing help capture dropouts
  • Module replacement should be a last step and may require vehicle-specific setup or security initialization
  • Because immobilizer involvement can affect starting, treat the code as potentially high impact

Vehicles Commonly Affected by U0167

  • Vehicles using a dedicated vehicle immobilizer control module on the network
  • Vehicles where immobilizer functions are integrated with multiple controllers that must communicate to authorize starting
  • Vehicles with extensive networked electronics and multiple communication buses or gateways
  • Vehicles operated in harsh environments that increase connector corrosion and harness wear
  • Vehicles with prior electrical repairs, accessory installations, or harness modifications that may disturb network wiring
  • Vehicles with underhood heat exposure contributing to wiring insulation damage or terminal relaxation
  • Vehicles with water intrusion history affecting control modules, connectors, or splice packs
  • Vehicles experiencing intermittent battery/ground issues that can reset modules and disrupt communication

FAQ

Does U0167 mean the vehicle immobilizer control module is bad?

No. U0167 only means other modules detected a loss of communication with the vehicle immobilizer control module. The cause could be power/ground loss, connector or wiring problems, or a network issue elsewhere. Confirm basics (power, ground, network integrity) before considering a module.

Can a weak battery cause U0167?

Yes, it can contribute. Low system voltage, poor battery connections, or weak grounds can cause modules to reset or drop off the network, which may be interpreted as a communication loss. Verify battery condition and perform voltage-drop checks on main power and ground paths.

Why does U0167 come and go?

Intermittent U0167 is often caused by a loose terminal, poor pin fit, corrosion, harness movement, or an intermittent power/ground connection. Logging network status while performing a careful wiggle test of related connectors and harness routing can help pinpoint the dropout.

Will clearing U0167 fix the problem?

Clearing the code only removes stored fault information; it does not correct the underlying communication problem. If the root cause remains, U0167 will typically return when the modules again detect lost communication with the vehicle immobilizer control module.

What should be checked first for U0167?

Start with simple, high-yield checks: verify the immobilizer module has stable power and ground, inspect connectors for corrosion or backed-out pins, and check the network wiring for opens/shorts or high resistance. Confirm whether other communication DTCs are present to guide isolation.

After repairs, confirm U0167 is resolved by verifying stable communication during a road test or extended idle test and rechecking for returning network DTCs.