P1506 VSS Signal Out of Range
The P1506 code is triggered when the Powertrain Control Module (PCM) detects that the Vehicle Speed Sensor (VSS) signal is outside the expected range during the KOEO (Key On Engine Off) or KOER (Key On Engine Running) self-test. The PCM compares the VSS reading against specific speed parameters; if the signal indicates motion when the vehicle should be stationary, or if the signal is missing or erratic when a valid input is expected, this manufacturer-specific fault is recorded.
01. Most Common Causes
- Faulty or internally worn Vehicle Speed Sensor (VSS)
- Open, short-to-ground, or short-to-reference voltage in the VSS circuit
- Corroded, bent pins, or poor contact at the VSS connector or harness
- Damaged or broken teeth on the VSS reluctor ring (if applicable)
- Incorrect operating conditions during self-test (e.g., vehicle moving when test started)
- Intermittent PCM failure or need for calibration update
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Speedometer may read zero or behave erratically
- Transmission may shift harshly or fail to shift properly
- Cruise control may be inoperative
03. Step-by-Step Diagnosis
Verify that the vehicle was stationary and the self-test was performed correctly
Inspect the VSS connector and wiring for damage, corrosion, or loose connections
Test the VSS resistance and output signal with a multimeter or oscilloscope
Check the reluctor ring for damage or missing teeth (if accessible)
If all else passes, perform a PCM calibration update or replace the PCM
1. Frequently Asked Questions
Is it safe to drive?▼
Yes, but you may experience transmission shifting issues and an inoperative speedometer. It's best to diagnose and repair soon to avoid further drivability problems.
How much does it cost to fix?▼
Typically $100–$300 for a VSS replacement, including parts and labor. PCM replacement or calibration can cost $500–$1,000 or more.