What Does P1185 Mean?
The common ground wire for the linear (wide-band) oxygen sensors is shorted to chassis ground. This creates incorrect ground reference voltage and disrupts proper sensor operation and air/fuel ratio control.
Safety Warning
Vehicle may run poorly with reduced power and fuel economy. Safe to drive short distances but should be repaired promptly.
Common Causes
40%
Chafed or damaged wiring rubbing against chassis or engine components
25%
Pinched ground wire during previous repair or installation
20%
Corroded connector allowing moisture to create ground path
15%
Improperly routed wiring touching hot exhaust components
Diagnostic Steps
1
Step 1: Disconnect O2 sensor connectors and measure resistance from ground circuit to chassis (should be infinite/open)
2
Step 2: Visually inspect entire O2 sensor wiring harness for chafing, damage, or improper routing
3
Step 3: Check wiring routing near exhaust components and sharp metal edges
4
Step 4: Test resistance between ground wire and all other sensor circuits (should be infinite when disconnected)
5
Step 5: Repair or replace damaged wiring section, ensure proper routing and protection from heat/abrasion
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
The common ground wire for the linear (wide-band) oxygen sensors is shorted to chassis ground. This creates incorrect ground reference voltage and disrupts proper sensor operation and air/fuel ratio control.
The most common cause of P1185 (Linear 02 Sensor / Common Ground Wire Short to ground) is: Chafed or damaged wiring rubbing against chassis or engine components
Typical repair costs for P1185 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may run poorly with reduced power and fuel economy. Safe to drive short distances but should be repaired promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1185 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System and Emissions Control
Difficulty
Type
Manufacturer
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