What Does P1087 Mean?
The upstream oxygen sensor on Bank 1 is responding too slowly when the ECM is commanding lean fuel conditions. This delayed response prevents proper closed-loop fuel control.
Common Causes
45%
Aging or contaminated oxygen sensor with reduced sensitivity
25%
Exhaust leak near oxygen sensor allowing air intrusion
15%
Contaminated sensor from oil consumption or coolant leak
10%
Poor electrical connection or damaged sensor wiring
5%
Low fuel pressure causing actual lean condition
Diagnostic Steps
1
Step 1: Monitor oxygen sensor voltage response time using scan tool graphing function
2
Step 2: Inspect exhaust system for leaks before and at oxygen sensor location
3
Step 3: Check oxygen sensor heater circuit operation and resistance
4
Step 4: Perform propane enrichment test and observe sensor response speed
5
Step 5: Inspect for signs of oil or coolant contamination on sensor element
Estimated Repair Cost
$150 - $400
Parts + labor, varies by vehicle and location
The upstream oxygen sensor on Bank 1 is responding too slowly when the ECM is commanding lean fuel conditions. This delayed response prevents proper closed-loop fuel control.
The most common cause of P1087 (O2 Sensor Circuit Slow Response in Lean Control Range (Bank 1 Sensor 1)) is: Aging or contaminated oxygen sensor with reduced sensitivity
Typical repair costs for P1087 range from $150 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive but will cause poor fuel economy and increased emissions. Extended driving may damage catalytic converter.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1087 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control and Fuel System
Difficulty
Type
Manufacturer
Recommended Tools
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