U0170 – Lost Communication With Steering Angle Sensor Module

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

Definition source: SAE J2012/J2012DA (industry standard)

DTC U0170 indicates the vehicle’s network detected a loss of communication with the Steering Angle Sensor Module. In practice, this means one or more control modules expected messages from that module but did not receive them within an allowed time, or the messages were invalid or not acknowledged. The exact modules involved, the enabling conditions, and how quickly the code sets can vary by vehicle, so always confirm the monitor description, network topology, and connector/pin assignments in the applicable service information. Because steering angle information is used by multiple driver-assist and stability functions, the impact may range from minor warning lamps to reduced support features, depending on how the platform manages missing data.

What Does U0170 Mean?

U0170 means Lost Communication With Steering Angle Sensor Module. Under SAE J2012 conventions, a “U” code relates to network communication, and this specific fault entry is used when the vehicle’s communication system cannot reliably exchange data with the Steering Angle Sensor Module. The code does not, by itself, prove the steering angle sensor is mechanically faulty; it indicates a communication failure condition detected by one or more modules on the network. Root cause can involve the network wiring, connector integrity, module power/ground, or the module itself, depending on vehicle design and test results.

Quick Reference

• Subsystem: Vehicle network communication involving the Steering Angle Sensor Module and related controllers.
• Common triggers: Module not powered up, poor ground, network open/short, connector fretting/corrosion, or intermittent harness faults causing message loss.
• Likely root-cause buckets: Wiring/connector issues, power/ground supply problems, Steering Angle Sensor Module fault, network faults, or control-module configuration/software issues (varies by vehicle).
• Severity: Typically moderate; may disable or reduce stability/traction/assist features and illuminate warnings; drivability may be normal but safety systems can be limited.
• First checks: Verify battery/charging health, check for multiple U-codes, confirm module power/ground, inspect network connectors/harness routing, and confirm the module is present on the network with a scan tool.
• Common mistakes: Replacing the steering angle sensor/module before verifying network integrity, ignoring related U-codes, or skipping power/ground and connector pin-fit checks.

Theory of Operation

The Steering Angle Sensor Module measures steering wheel position and direction of rotation, then shares that information over the vehicle communication network so other modules can calculate stability corrections, steering assist strategies, and driver-assist functions. Depending on the platform, the sensor may be integrated into a module assembly or communicate through a dedicated module that broadcasts steering angle data as network messages.

To detect a communication loss, receiving modules monitor for expected messages at regular intervals and also verify message validity (such as counters, checks, or plausibility rules that vary by vehicle). If messages stop arriving, arrive corrupted, or the module does not respond on the network, the receiving module(s) will flag a loss-of-communication condition and store U0170, often along with other network-related codes that help identify whether the issue is local to the module, its power/ground, or the shared network.

Symptoms

• Warning lamps: Stability control/traction control/steering-related warning indicators illuminated.
• Driver-assist limitation: Certain assist features may be reduced, unavailable, or show “service” messages.
• Stability behavior: Stability/traction interventions may be disabled or operate in a limited fallback mode.
• Steering feel: Steering assist strategy may change or default, depending on vehicle design.
• Stored network codes: Multiple U-codes in several modules, often pointing to a shared network or power issue.
• Intermittent faults: Symptoms may appear during turns, bumps, or when the harness/connector is disturbed.

Common Causes

• Open, shorted, or high-resistance wiring on the network communication circuits between the steering angle sensor module and the rest of the vehicle network
• Poor terminal fit, corrosion, moisture intrusion, or connector damage at the steering angle sensor module, related junctions, or network splices
• Loss of power feed(s) to the steering angle sensor module due to an open fuse, faulty relay (where used), or open in the power supply circuit
• High resistance or open ground path for the steering angle sensor module (including loose ground fasteners or damaged ground wiring)
• Intermittent connection caused by harness strain, chafing against brackets, prior repairs, or pinched wiring near the steering column/dash area (varies by vehicle)
• Network backbone issue affecting multiple modules (damaged main bus wiring, failed splice pack, or poor connection at a gateway/junction, where applicable)
• Steering angle sensor module internal fault that prevents it from communicating on the network
• Configuration or software-related issue after service work (module setup, coding, or initialization requirements vary by vehicle and service information)

Diagnosis Steps

Tools typically needed include a scan tool capable of reading network DTCs from multiple modules and viewing live data, a digital multimeter, and vehicle-specific wiring diagrams/service information. A backprobe kit, terminal inspection tools, and basic hand tools help with connector checks. If available, a lab scope can help assess network signal integrity, but many faults can be isolated with careful power/ground and continuity testing.

1. Confirm the code is present and record freeze-frame/event data where available. Note which module reports U0170 and whether other network or steering-related DTCs are stored, especially additional “lost communication” codes that may indicate a wider network problem.
2. Check scan tool module list/topology. Determine whether the steering angle sensor module is missing/offline or intermittently present. If the module communicates at times, prioritize intermittent wiring/connector faults and plan to perform a wiggle test with live monitoring.
3. Clear DTCs and perform a controlled key cycle/road test (as safe and appropriate). Re-check for U0170. A code that returns immediately after key-on often points to power/ground loss, a hard open, or a module that is not booting onto the network.
4. Inspect basics first: verify battery condition and system voltage stability, then visually inspect fuses and any labeled feeds supplying the steering angle sensor module. Do not rely on a visual fuse check alone; verify power is present on both sides of the fuse with the circuit loaded (per service info).
5. Perform a targeted visual inspection of the module area and harness routing (varies by vehicle). Look for chafing, pinched sections, prior repairs, loose connectors, water tracks, damaged conduit, and disturbed grounds near the steering column/dash harness path.
6. Check the steering angle sensor module power and ground circuits. With the connector accessed, verify the module has the required power feed(s) and a solid ground. Use voltage-drop testing on the ground path and on the power feed under load to find hidden resistance; compare results to service information guidance.
7. If power/ground are good, evaluate the network communication circuits at the module connector. Inspect terminals for spread, push-outs, corrosion, or poor pin fit. With key off (and following service information precautions), perform continuity checks between the module connector and the next network junction/splice and check for shorts between network lines and to power/ground.
8. Perform a wiggle test while monitoring live data/module status on the scan tool. Gently manipulate the harness near the steering angle sensor module connector, along known routing points, and at splice/junction locations. Watch for the module dropping offline, communication errors, or changes in related live parameters.
9. If available, use a lab scope to assess network signal quality at a convenient access point and compare to known-good patterns for that platform (consult service information). Look for evidence of line noise, signal collapse, or a line being held dominant/recessive, which can indicate a wiring fault or a module loading the bus.
10. Isolate whether the issue is local to the steering angle sensor module or a broader network problem. If multiple modules are offline, prioritize diagnosing the network backbone, gateway/junction connections, and main splices. If only the steering angle sensor module is affected and wiring checks out, suspect the module or its setup requirements.
11. After repairs, clear codes and perform a verification drive cycle appropriate for the vehicle. Re-scan all modules to confirm U0170 does not return and confirm steering angle-related live data is plausible and stable without dropouts, per service information.

Professional tip: If U0170 is intermittent, focus on reproducing the dropout while logging scan tool data (module presence, bus errors, and steering angle-related parameters). Intermittent communication losses are frequently caused by slight terminal tension issues or harness movement near connectors/splices; terminal inspection and voltage-drop testing under real load often find problems that simple ohmmeter checks miss.

Possible Fixes & Repair Costs

Repair costs for U0170 vary widely because the fix depends on where communication is being lost: power/ground, network wiring, connector condition, a sensor/module fault, or a configuration issue. Labor can also differ based on access and required setup procedures.

• Repair or replace damaged network wiring (twisted pair where used) between the steering angle sensor module and the network, then verify restored communication
• Clean, reseat, repair, or replace affected connectors/terminals (poor pin fit, corrosion, backed-out terminals, or water intrusion) and confirm stable contact
• Restore correct power and ground to the steering angle sensor module (repair opens, high resistance, loose grounds, or blown feed protection as applicable)
• Perform voltage-drop based repairs on suspect power/ground circuits after identifying excessive resistance at splices, crimps, or ground points
• Replace the steering angle sensor module only after confirming network integrity and correct power/ground (and follow any required setup/calibration procedures per service information)
• Reconfigure/reinitialize related control modules when required by the platform after parts replacement or network repairs (procedure varies by vehicle)

Can I Still Drive With U0170?

You may be able to drive, but caution is warranted because steering angle information can be used by stability/traction control and other safety functions. If warning lights are present, steering/braking behavior feels abnormal, or the vehicle enters a reduced-assist/safety mode, avoid driving and have it diagnosed. If additional network codes appear, symptoms worsen during turns, or communication faults are intermittent, treat it as a priority repair and verify with service information for your vehicle.

What Happens If You Ignore U0170?

Ignoring U0170 can lead to recurring warning lights and reduced or disabled stability/traction features that rely on steering angle input. The communication fault may become more frequent, expand to additional modules on the network, and complicate diagnosis later. Intermittent losses can also create inconsistent behavior in related systems and may reduce overall system reliability.

Last updated: March 17, 2026

Vehicles Commonly Affected by U0170

• Vehicles with a networked steering angle sensor module communicating over a body/chassis network
• Vehicles equipped with electronic stability control and traction control that use steering angle input
• Vehicles with electric power steering or advanced steering assist features that reference steering angle data
• Vehicles with multiple network gateways where a single gateway fault can disrupt module communication
• Vehicles exposed to vibration or steering column movement that stresses wiring and connectors
• Vehicles with prior steering/suspension work where connectors were disturbed or harness routing changed
• Vehicles with water intrusion risk near footwells, kick panels, or steering column area (location varies by vehicle)
• Vehicles with aftermarket electrical additions that share grounds or affect network routing (design impact varies)

Always confirm the repair by clearing codes, cycling ignition, and performing a controlled road test while logging network/module data to ensure the steering angle sensor module stays online without dropouts.