A loose, corroded, or backed-out terminal in the connector at the restraints system sensor 'A'; Damaged or chafed wiring in the harness between the sensor and the module it reports to; A failed restraints system sensor 'A' that no longer transmits on the network; Water intrusion or corrosion in a connector or splice pack along the communication bus; A poor ground or power feed to the sensor or to the module that monitors it; A fault in the module itself that has disabled its network transceiver; Aftermarket accessories or previous repairs that disturbed the SRS harness

DTC codes / U01xx · Lost communication with a control module / U0170

U0170Lost Communication With 'Restraints System Sensor A'

Q: What does code U0170 mean?

Lost Communication With 'Restraints System Sensor A'. U0170 is a generic network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has lost contact with the restraints system sensor designated as 'A'. The module that sets this code has detected that the expected periodic messages from that sensor have stopped arriving within the required time window, which points to a break in the communication path rather than a confirmed sensor failure.

U0170 is a generic network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has lost contact with the restraints system sensor designated as 'A'. The module that sets this code has detected that the expected periodic messages from that sensor have stopped arriving within the required time window, which points to a break in the communication path rather than a confirmed sensor failure.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

The supplemental restraint system (SRS) warning light stays illuminated after the bulb check
A message on the driver information display stating that the restraint system needs service
The airbag system may be disabled or placed in a default reduced-protection mode
Often no symptoms besides the warning light, with the vehicle driving normally
Intermittent warning light operation over bumps or in wet weather if the fault is a loose connection
Other unrelated warning lights may appear if the fault is a shared network bus issue

Common causes, most likely first

A loose, corroded, or backed-out terminal in the connector at the restraints system sensor 'A'
Damaged or chafed wiring in the harness between the sensor and the module it reports to
A failed restraints system sensor 'A' that no longer transmits on the network
Water intrusion or corrosion in a connector or splice pack along the communication bus
A poor ground or power feed to the sensor or to the module that monitors it
A fault in the module itself that has disabled its network transceiver
Aftermarket accessories or previous repairs that disturbed the SRS harness

How to diagnose and fix it

Connect a scan tool and record all stored codes in every module, then note whether U0170 is current or history
Inspect the connector at restraints system sensor 'A' for corrosion, loose pins, and proper seating, then reseat it
Check the sensor's power, ground, and communication voltage with a multimeter or oscilloscope at the connector
Perform a wiggle test on the harness while watching live network data to expose an intermittent connection
Repair or replace damaged wiring and terminals, then clear the code and verify communication returns
If wiring and power checks pass, substitute a known-good sensor of the same part type and recheck
If the sensor communicates on a bench test but not in the vehicle, diagnose the module's network side before replacing it

What U0170 does not always mean

This code rarely means the sensor itself has failed; a loose pin or chafed wire in the SRS harness is the far more common root cause.
A weak or failing battery can cause modules to drop off the bus and set communication codes, so always check charging system health before condemning parts.
Because restraints system sensor 'A' is a generic label, the actual component varies by make and model, so consult the vehicle-specific service information before ordering anything.
U0170 can be stored as a history code after a prior repair or a disconnected connector, and clearing it may be all that is required if it does not return.
A fault in a shared splice pack or ground point can set U0170 alongside codes for other modules, so look at the full code list rather than this code alone.

Can I keep driving with U0170?

The vehicle will usually drive normally, but the airbag system may be disabled while this code is present, so avoid aggressive driving and get it diagnosed promptly. Do not ignore the warning light, because restraint protection may not deploy in a collision.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.