🔍 Sensor Role
The Chevrolet Code P1391 is related to the performance of the G sensor circuit of the wheel speed sensor 1.
This code is an important indicator for Chevrolet vehicle owners, signaling a potential problem that could affect the vehicle’s safety and performance. Understanding the Chevrolet Code P1391 can help you make informed decisions regarding your car’s maintenance and repairs.
It is essential to know that the speed sensor is also used for the stability control system, which helps prevent skidding during difficult driving conditions. Proper functioning of this sensor can prevent accidents and improve the vehicle’s overall safety.
The wheel speed sensor 1 (usually the front left wheel) is critical for:
- ABS Braking
- Traction Control
- Electronic Stability Control (ESC)
- Speed Calibration (speedometer, transmission management)
⚠️ Immediate Symptoms
Another important point to consider is that the speed sensor plays a crucial role in the operation of modern driver assistance systems, such as adaptive cruise control. Any malfunction of this sensor could therefore disrupt these advanced features.
- ABS + Traction Warning Lights illuminated on the dashboard
- Deactivation of ABS Braking (risk of wheel lock-up)
- Erratic behavior of the speedometer
- Loss of stability control during turns
- Possible engine stalling during acceleration (on automatic transmission models)
Drivers may also notice changes in their vehicle’s performance, such as less smooth acceleration or jerking while driving. These signs can often be attributed to a problem with the speed sensor.
Furthermore, if the ABS and traction warning lights come on, it is advisable to avoid driving the vehicle, as this could lead to dangerous situations. When these indicators appear, it is best to have the vehicle inspected immediately by a professional.
🔧 Common Causes on Chevrolet
| Frequency | Cause | Sensitive Models |
|---|---|---|
| 50% | Faulty sensor | Silverado, Tahoe, Equinox (2010-2018) |
| 25% | Damaged wiring | Traverse, Malibu (connectors near wheel well) |
| 15% | Dirty/deteriorated tone ring | Impala, Cruze (mud/grease buildup) |
| 7% | Mechanical play (bearing) | Colorado, TrailBlazer |
| 3% | ABS module failure | Rare cases – requires advanced diagnosis |
🛠️ Diagnosis in 3 Steps
1. Visual Inspection (20 min)
- Locate the front left wheel sensor (behind the brake disc).
- Check:
- Electrical connector (frequent corrosion on Silverado).
- Sensor/reluctor gap (0.3–1.0 mm).
- Cleanliness of the tone ring (clean with brake cleaner).
2. Electrical Tests
| Test | Tool | Normal Values |
|---|---|---|
| Resistance | Multimeter | 850–1350 Ω (depending on model) |
| AC Voltage | Oscilloscope | Signal > 0.35V (wheel rotating at 60 rpm) |
| Power Supply | DC Multimeter | 12V with ignition ON |
Diagnosing problems related to the speed sensor can be complex and often requires specific technical skills. Garages equipped with advanced diagnostic tools can quickly identify problems and provide appropriate solutions.
3. Advanced Scan
- Use a GM MDI or Tech2 scanner to:
- Read live data (wheel speeds compared).
- Check for companion codes (e.g., C1391 = ABS module problem).
💰 Solutions & Costs
| Problem | Repair | Average Cost |
|---|---|---|
| Faulty Sensor | Replacement (ACDelco) | $70–140 (part) + 0.5h labor |
| Damaged Wiring | Harness repair | $100–250 |
| Tone Ring | Cleaning/replacement | $30–200 |
| ABS Module | Reprogramming/replacement | $400–900 |
⏱️ Service Time: 1h (diagnosis) + 1h to 2h (repair).
🚨 Safety Emergencies
Do not drive if:
- The ABS/traction warning lights are flashing.
- Metallic grinding noises are heard at low speeds.
- The steering becomes heavy during turns.
→ Risk of total loss of controlled braking!
In summary, it is crucial to pay attention to alerts regarding the Chevrolet Code P1391. Ignoring the symptoms and delaying repairs can lead to more serious problems and higher repair costs in the long term.
- Specific Parts:
- ACDelco sensor 213-928 (Silverado) or 213-3065 (Equinox).
- Reset:
- Clear codes via OBD-II + road test at 40 km/h (don’t forget sharp turns).
- Anti-corrosion:
- Apply dielectric grease to connectors (especially on Cruze/Impala).
- Common Mistake:
- Do not confuse P1391 (circuit problem) with P1392 (intermittent signal).
📊 Workshop Data: 80% of P1391 codes on Chevrolet resolved by sensor replacement + reluctor cleaning.
Conclusion:
A P1391 code on Chevrolet disables vital safety systems. Recommended procedure:
- Check front left wheel wiring and connector.
- Test the sensor (resistance/signal).
- Clean/adjust the tone ring.
- Replace the sensor if necessary → Reset the ECM.
Do not ignore this code: A faulty ABS increases braking distances by 30% on wet roads!
It is also recommended to keep records of previous repairs and error codes. This can help technicians better understand the vehicle’s history and avoid redundant diagnostics.
As vehicles age, it is normal for some parts to start showing signs of wear. Regular maintenance can help detect problems before they become serious. This includes checking speed sensors, wiring, and connectors for any corrosion or damage.
In conclusion, the Chevrolet Code P1391 should not be taken lightly. Addressing this code quickly can not only improve your vehicle’s performance but also ensure your safety and that of others on the road.