What Does C1742 Mean?
The rear parking sounder (audible warning buzzer) circuit has a failure. The parking assist module cannot drive the rear sounder to produce audible proximity warnings. The visual display may still function, but the driver will not hear beeps when approaching obstacles while reversing. This is often caused by a broken wire, failed sounder unit, or connector issue.
Common Causes
30%
Failed rear sounder unit — burned-out piezo element or broken internal connection
25%
Open circuit in the wiring between the parking module and the rear sounder
25%
Corroded or disconnected connector at the rear sounder location
15%
Sounder physically damaged by water intrusion, impact, or cabin moisture
5%
Parking assist module output driver failure for the sounder circuit
Diagnostic Steps
1
Locate the rear parking sounder (typically mounted behind the rear bumper trim, in the trunk area, or behind the rear interior panel) and verify the connector is securely attached.
2
With the connector disconnected, measure the sounder's resistance — a typical piezo sounder reads between 20-100 ohms. An open reading (OL) means the sounder element is burned out.
3
Check for 12V from the module at the sounder connector while the parking system is active and detecting an obstacle — if voltage is present but the sounder is silent, the sounder is faulty.
4
If no voltage at the sounder connector, check wiring continuity back to the parking assist module. Also verify the ground circuit for the sounder.
5
Temporarily connect a known-good sounder or a small test lamp to the sounder connector — if it illuminates or sounds during reverse parking, the wiring is good and the original sounder needs replacement.
Estimated Repair Cost
$30 - $200
Parts + labor, varies by vehicle and location
The rear parking sounder (audible warning buzzer) circuit has a failure. The parking assist module cannot drive the rear sounder to produce audible proximity warnings. The visual display may still function, but the driver will not hear beeps when approaching obstacles while reversing. This is often ...
The most common cause of C1742 (Rear Sounder Circuit Failure) is: Failed rear sounder unit — burned-out piezo element or broken internal connection
Typical repair costs for C1742 range from $30 to $200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is safe to drive. You will not receive audible parking warnings when reversing, which reduces situational awareness in tight spaces. The visual parking display (if equipped) should still function. Use extra caution and rely on mirrors and cameras when reversing until the sounder is repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1742 to identify the root cause.
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Quick Info
Category
Chassis
System
Parking Assist System
Difficulty
Type
Manufacturer
Recommended Tools
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