Damaged or corroded wiring harness at the wheel speed sensor connector, often from road debris or moisture intrusion; Failed wheel speed sensor itself, particularly the sensor at the affected wheel (sensor 2); Debris or metallic particles stuck to the sensor tip or tone ring, disrupting the signal; Worn or damaged tone ring (reluctor ring) on the hub or axle, causing an erratic signal; Poor ground connection for the sensor or module, leading to a low-voltage reference; Faulty ABS control module or body control module, though this is less common than wiring issues; Aftermarket or incorrect sensor installed previously that does not meet GM voltage specifications

DTC codes / GM codes / P1397

P1397 · GMWheel Speed Sensor 2 G-Sensor Circuit Low Voltage

Q: What does code P1397 mean?

Wheel Speed Sensor 2 G-Sensor Circuit Low Voltage. P1397 on a GM vehicle means the body control module or ABS control module has detected a low-voltage condition on the signal circuit for wheel speed sensor 2, which is often paired with a G-sensor (acceleration sensor) input on the same harness. The computer expects a fluctuating voltage from that sensor as the wheel rotates, but the signal stays below the acceptable threshold, so it flags the circuit as faulty and may disable traction control or anti-lock braking.

P1397 on a GM vehicle means the body control module or ABS control module has detected a low-voltage condition on the signal circuit for wheel speed sensor 2, which is often paired with a G-sensor (acceleration sensor) input on the same harness. The computer expects a fluctuating voltage from that sensor as the wheel rotates, but the signal stays below the acceptable threshold, so it flags the circuit as faulty and may disable traction control or anti-lock braking.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Anti-lock brake system (ABS) warning light illuminated on the dashboard
Traction control or stability control warning light on, with the system disabled
Speedometer may read erratically or drop to zero intermittently
Brake pedal may feel different or pulsate during low-speed stops if ABS is disabled
Often no symptoms besides the warning light, especially if the fault is intermittent
Cruise control may stop working because it relies on vehicle speed data

Common causes, most likely first

Damaged or corroded wiring harness at the wheel speed sensor connector, often from road debris or moisture intrusion
Failed wheel speed sensor itself, particularly the sensor at the affected wheel (sensor 2)
Debris or metallic particles stuck to the sensor tip or tone ring, disrupting the signal
Worn or damaged tone ring (reluctor ring) on the hub or axle, causing an erratic signal
Poor ground connection for the sensor or module, leading to a low-voltage reference
Faulty ABS control module or body control module, though this is less common than wiring issues
Aftermarket or incorrect sensor installed previously that does not meet GM voltage specifications

How to diagnose and fix it

Inspect the wheel speed sensor 2 connector and harness for corrosion, chafing, or loose pins, and clean or repair as needed
Remove the sensor and check the tip and tone ring for metallic debris or damage, then clean or replace the tone ring if worn
Measure resistance and voltage output of the sensor while spinning the wheel by hand, comparing to GM specifications
Check the sensor signal circuit for a short to ground or an open circuit using a multimeter and wiring diagram
Verify the ground circuit for the sensor and module is clean and tight, repairing any corroded ground points
If the sensor and wiring test good, perform a module scan for stored codes and live data to confirm the signal dropout
Replace the wheel speed sensor 2 if it fails electrical testing, then clear codes and verify the ABS and traction control systems operate correctly

What a low G-sensor voltage really means

On many GM platforms, wheel speed sensor 2 shares a circuit or connector with the G-sensor (acceleration sensor), so a fault in the G-sensor wiring can set P1397 even when the wheel speed sensor itself is fine.
A common misdiagnosis is replacing the ABS module when the actual problem is a chafed wire behind the wheel well liner that only shorts when the suspension compresses over bumps.
Metallic debris from a worn brake rotor or hub bearing can stick to the sensor tip and cause a low-voltage signal that looks like a failed sensor, so always clean the sensor and tone ring before condemning parts.
Intermittent P1397 codes often appear after tire rotation or brake service because the sensor connector was disturbed, so check recent service history before diving into complex diagnostics.
The code does not always mean the sensor is dead; a weak battery or charging system fault can cause low reference voltage to multiple sensors, so verify system voltage first.

Can I keep driving with P1397?

You can usually drive the vehicle with P1397 set, but the ABS and traction control systems may be disabled, which reduces safety in slippery conditions or emergency braking. Avoid hard braking on wet or loose surfaces and get the fault diagnosed soon, especially if the brake warning light is also on.

Tools that help

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