C0139 moderate

Longitudinal Acceleration Sensor Circuit Malfunction

The C0139 code means the vehicle's onboard diagnostic system has detected: Longitudinal Acceleration Sensor Circuit Malfunction. This is a moderate severity code.

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Keep driving?: Short distances only
DIY difficulty: hard
Estimated cost: $150 - $500 (parts and labor)

Read ABS Codes

BlueDriver Bluetooth Pro Scanner

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Read ABS Codes

LAUNCH CRP123X (Reads ABS + Chassis)

Basic scanners cannot read ABS codes. This one reads all four systems so you know exactly which sensor failed.

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Common Symptoms

Stability control warning on
Hill descent control disabled
Brake assist not functioning optimally
ESC fault message
Dynamic traction control inactive

Probable Causes (Ranked by Likelihood)

Failed longitudinal acceleration sensor Very High
Sensor mounting shifted or loose High
Corroded sensor wiring connector Moderate
ESC module sensor processing fault Low

Step-by-Step Diagnostic Procedure

Scan ESC module for longitudinal acceleration DTCs
Read sensor data on level surface at rest and during braking
Check sensor mounting for secure attachment
Inspect connector and wiring for damage
Compare readings to specifications

Frequently Asked Questions

What is a longitudinal acceleration sensor?

It measures the forward and backward forces on the vehicle during acceleration and braking. This data helps the ESC system manage hill descent control and brake force distribution.

Is this sensor found on all vehicles?

Not all vehicles have a dedicated longitudinal sensor. Many combine yaw rate, lateral, and longitudinal sensing into a single inertial measurement unit or sensor cluster.

Does this affect hill descent control?

Yes. Hill descent control relies on the longitudinal sensor to measure the vehicle pitch angle and rate of descent. Without valid data, the system will disable itself.