Intermittent Vehicle Speed Sensor Signal
The P1505 code indicates that the Powertrain Control Module (PCM) has detected an intermittent or erratic signal from the Vehicle Speed Sensor (VSS). The VSS monitors the rotational speed of the wheels or transmission output shaft and is critical for functions such as cruise control, power steering assist, speedometer operation, and transmission shift scheduling. An intermittent signal means the sensor output fluctuates or drops out momentarily, not matching actual vehicle speed, making diagnosis challenging as the fault may not be constant.
01. Most Common Causes
- Faulty or internally worn Vehicle Speed Sensor (VSS)
- Corroded, oxidized, or loose pins in the VSS connector
- Intermittent short to ground or voltage in VSS wiring
- Intermittent open circuit in VSS wiring
- Damaged tone wheel or reluctor ring (broken or misaligned teeth)
- Intermittent PCM failure
02. Symptoms You Will Notice
- Speedometer reading erratic or dropping to zero
- Cruise control disengaging or not working
- Harsh or delayed transmission shifts
- Check Engine Light illuminated
- Loss of power steering assist at low speeds
03. Step-by-Step Diagnosis
Scan for codes and record freeze frame data
Inspect VSS connector and wiring for corrosion, damage, or loose connections
Test VSS output signal with a digital multimeter or oscilloscope while driving
Check tone wheel for damage or debris
If signal is intermittent, perform a wiggle test on wiring harness
Replace VSS if tests indicate failure; if problem persists, check PCM
1. Frequently Asked Questions
Is it safe to drive?▼
You can usually drive short distances, but the vehicle may experience erratic speedometer, transmission shifting issues, and loss of cruise control. It's best to diagnose and repair promptly to avoid further drivability problems.
How much does it cost to fix?▼
Repair costs typically range from $100 to $300, including parts and labor. A VSS replacement is often $50-$150 for the sensor and $50-$150 for labor, depending on vehicle accessibility.