What Does P1190 Mean?
The linear oxygen sensor reference voltage signal is out of expected range or unstable. This prevents accurate air-fuel ratio measurement and closed-loop fuel control.
Common Causes
40%
Failed linear oxygen sensor with degraded reference cell
25%
Poor ground connection at oxygen sensor or ECU
20%
ECU power supply voltage irregularities affecting sensor reference voltage
10%
Damaged or corroded wiring in reference voltage circuit
5%
ECU internal voltage regulator fault
Diagnostic Steps
1
Step 1: Verify battery voltage is stable (12.5-14.5V) and check main power supply to ECU
2
Step 2: Measure reference voltage at oxygen sensor connector with key on, engine off (typically 2.5-5V)
3
Step 3: Check all ground connections at sensor, ECU, and engine block for cleanliness and tightness
4
Step 4: Monitor reference voltage with scanner in live data while engine runs to check for fluctuations
5
Step 5: If voltage is stable at ECU side but incorrect at sensor, check wiring continuity and resistance
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
The linear oxygen sensor reference voltage signal is out of expected range or unstable. This prevents accurate air-fuel ratio measurement and closed-loop fuel control.
The most common cause of P1190 (Linear 02 Sensor / Reference Voltage Incorrect Signal) is: Failed linear oxygen sensor with degraded reference cell
Typical repair costs for P1190 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but will operate in open-loop mode with reduced performance and fuel economy.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1190 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Fuel System / Emissions Control
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
