U0159 – Lost Communication With Parking Assist Control Module “B”

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

Definition source: SAE J2012/J2012DA (industry standard)

DTC U0159 indicates the vehicle has detected a loss of communication with Parking Assist Control Module “B” over the network. In practice, this means other modules expected to receive messages from that parking assist module but did not see them within the required time window, or the module could not be reached during a network check. The exact conditions that set U0159 (timers, message IDs, and which module stores the code) can vary by vehicle, so confirm the monitor description, network topology, and pinpoint tests using the appropriate service information. This code points to a network communication problem and should be approached with power/ground, wiring, and network integrity checks before replacing modules.

What Does U0159 Mean?

U0159 means “Lost Communication With Parking Assist Control Module ‘B’.” Based on the official definition, the fault is not a direct sensor reading issue; it is a network-level communication fault where one or more controllers cannot exchange expected data with the parking assist control module identified as “B.” SAE J2012 defines the standardized structure for U-codes as network communication diagnostics, which typically set when required messages are missing, corrupted, or the module is offline/unreachable. The code does not, by itself, prove the parking assist module is bad; it indicates that the communication path and/or module availability must be verified.

Quick Reference

• Subsystem: Vehicle network communications related to Parking Assist Control Module “B”
• Common triggers: Module not powering up, network bus disruption, open/shorted communication lines, high resistance at connectors, or intermittent connection
• Likely root-cause buckets: Wiring/connector issues, power/ground supply issues, network integrity problems, module fault, configuration/software issues (varies by vehicle)
• Severity: Usually moderate; parking assist features may be disabled and warnings may display, but basic driving may remain normal (varies by vehicle)
• First checks: Verify battery/charging health, check for related network DTCs, confirm module power/ground and connector condition, inspect harness routing and network splices
• Common mistakes: Replacing the module before confirming power/ground, ignoring other network codes, or overlooking intermittent connector pin fit/corrosion

Theory of Operation

Parking assist functions are coordinated by a dedicated control module that exchanges data with other controllers over the vehicle network. Depending on design, this module may process inputs from parking-related sensors and then broadcast status, warnings, and requests to other modules (for example, to command alerts or provide information to a display). Other modules expect periodic network messages and also may perform presence checks to confirm the module is online.

U0159 sets when those expected communications with Parking Assist Control Module “B” are not received for a calibrated period or the module cannot be reached during network communication routines. Typical underlying reasons include the module losing power/ground, a disrupted network connection (open/short/high resistance), or an intermittent connection that causes dropouts. Exact message timing and which controller logs the DTC vary by vehicle, so service information is needed for precise criteria.

Symptoms

• Warning message: Parking assist or driver-assistance warning displayed
• Inoperative feature: Parking assist system disabled or unavailable
• No audible alerts: Missing tones/chimes normally associated with parking assist
• Indicator behavior: Parking assist indicator lamp on, flashing, or showing a fault state
• Multiple DTCs: Additional network communication codes stored in other modules
• Intermittent operation: Feature works sometimes, then drops out over bumps or during moisture/temperature changes
• Reduced information: Missing parking assist status data in scan tool live data on one or more modules

Common Causes

• Open circuit, short, or high resistance in the network communication wiring between the Parking Assist Control Module “B” and the rest of the network
• Poor connector contact (backed-out terminals, corrosion, bent pins, inadequate pin tension) at the Parking Assist Control Module “B” or an inline network connector
• Power feed issue to the Parking Assist Control Module “B” (blown fuse, faulty relay, open in the supply circuit)
• Ground circuit issue for the Parking Assist Control Module “B” (loose ground fastener, corrosion at ground point, open/high resistance ground path)
• Network short to power, short to ground, or intermittent short caused by harness chafing or water intrusion (varies by vehicle routing and sealing)
• Loose module connection or improper seating/locking of the module connector after prior service
• Network-related issue elsewhere on the same bus that disrupts communications and causes multiple modules to report lost-communication codes
• Parking Assist Control Module “B” internal fault or software issue (consider only after power/ground and network integrity are verified)

Diagnosis Steps

Tools that help include a scan tool capable of full-module network scans and reading freeze-frame/code details, a digital multimeter for continuity and voltage-drop checks, and access to vehicle-specific wiring diagrams and connector views. Backprobing tools and terminal test adapters are useful to avoid damage. If available, a breakout box or network test tool can speed isolation, but it is not required.

1. Confirm the code and capture context: Verify U0159 is present and note whether it is current or history. Record freeze-frame or fault context data and run a complete module scan to see if other communication codes are also present.
2. Check if the module is reachable: Attempt to communicate directly with Parking Assist Control Module “B” using the scan tool. If it is reachable, prioritize intermittent connection, power/ground integrity, or network noise; if it is not reachable, focus on power/ground and bus wiring first.
3. Assess the pattern of network faults: If multiple modules report lost communication, treat this as a network-wide issue until proven otherwise. If U0159 is isolated to one module, focus on that module’s power/ground, connector, and its local network branch.
4. Perform a basic electrical triage: Inspect related fuses and relays feeding the module (varies by vehicle). Check for signs of repeated fuse failures or evidence of overheating at fuse/relay sockets that could cause intermittent supply loss.
5. Visual inspection of module area and harness: With ignition off, inspect the module connectors, harness routing, and nearby splice/connector points for damage, chafing, pinch points, moisture intrusion, or prior repair. Confirm connectors are fully seated and locks are engaged.
6. Verify power and ground at the module: Using wiring diagrams, identify module power feeds and grounds. With the circuit powered as specified by service information, check for proper supply presence and perform voltage-drop testing on grounds and power feeds under load to identify hidden resistance (do not rely on ohms checks alone).
7. Check network circuit integrity to the module: With ignition off and following service information precautions, test continuity from the module connector to the appropriate network splice/connector points. Check for open circuits and unwanted continuity to ground or power that would indicate shorts.
8. Wiggle test for intermittents: While monitoring scan-tool communication status and live data (or network health indicators where available), wiggle the harness and gently manipulate the connector at the module and along suspect routing areas. A drop-out strongly suggests a connector/terminal or harness fault.
9. Inspect terminals closely: If the fault points to the connector, disconnect it and inspect terminal condition and pin fit. Look for spread terminals, corrosion, fretting, or pushed-back pins. Use appropriate terminal tension checks per service information; repair or replace terminals as needed.
10. Evaluate network behavior with live logging: If the module is intermittently reachable, perform an extended road-test or stationary run while logging the network module list/communication status. Correlate dropouts with vibration, steering movement, or accessory loads to narrow location and conditions.
11. Isolate before condemning the module: Only after power/ground integrity, connector condition, and network wiring checks pass, consider Parking Assist Control Module “B” as suspect. If replacement/programming is required, follow service information procedures (setup, coding, calibrations vary by vehicle).

Professional tip: When U0159 is intermittent, the fastest path is often to prove whether the module is losing power/ground or losing the network signal. Use live-data logging to watch the module’s presence on the network while simultaneously performing a targeted wiggle test and voltage-drop checks; this prevents replacing a module when the real issue is a high-resistance ground or a marginal terminal.

Possible Fixes & Repair Costs

Repair cost for U0159 varies widely because the underlying issue can range from a simple connector problem to a module power/ground fault or a network wiring repair. Diagnosis time, parts availability, and labor access all strongly influence the final total.

• Clean, reseat, and secure connectors related to the Parking Assist Control Module “B” and the network junctions it relies on; repair poor pin fit or terminal tension issues found during inspection
• Repair or replace damaged wiring in the communication network (for example, chafed, pinched, stretched, or corroded conductors) after confirming the fault with testing
• Restore missing power or ground to the Parking Assist Control Module “B” by repairing the affected feed, fuse link, relay control, ground point, or high-resistance connection verified by voltage-drop testing
• Address water intrusion or corrosion at connectors by correcting the source of intrusion and replacing terminals/connector bodies as needed (only when confirmed)
• Reprogram, configure, or perform a module setup procedure if service information calls for it after network/power integrity is confirmed
• Replace the Parking Assist Control Module “B” only after proving power, ground, and network circuits are correct and the module is not communicating when commanded

Can I Still Drive With U0159?

In many vehicles, U0159 mainly affects parking assist operation, so basic driving may still be possible; however, your parking aid features may be disabled or unreliable. If any critical warnings appear (such as brake, steering, stability control, or widespread network faults), or if the vehicle shows abnormal behavior, avoid driving and diagnose the network/power issue first because communication problems can affect multiple systems.

What Happens If You Ignore U0159?

Ignoring U0159 can lead to loss of parking assist functionality, intermittent warnings, and recurring faults that become harder to diagnose as the issue worsens (for example, corrosion spreading or a harness chafe progressing). If the root cause is a network or power/ground problem, additional modules may begin reporting communication codes, increasing the risk of broader feature disruptions.

Last updated: March 15, 2026

Vehicles Commonly Affected by U0159

• Vehicles equipped with multi-sensor parking assist systems that use a dedicated control module
• Vehicles with multiple parking assist modules (for example, separate front/rear or “A/B” module architectures)
• Vehicles where the parking assist module is located in areas prone to moisture or debris exposure (location varies by vehicle)
• Vehicles with recent rear bumper, fascia, hitch, or body repairs where harness routing or connector seating may be disturbed
• Vehicles with prior battery replacement, low-voltage events, or jump-start incidents affecting network module wake-up
• Vehicles with known harness flex points (tailgate, trunk hinge, bumper corners) that can stress wiring over time
• Vehicles with accessory additions that share power/ground points or routing paths near parking assist wiring
• Vehicles operating in environments that accelerate corrosion at low-mounted connectors (road spray, salt, frequent washing)

If U0159 returns after clearing, focus on verifying module power/ground integrity and network wiring/connectors before replacing any components.