Q: Check Engine light; upstream O2 sensor

asked by on

The Check Engine light is on again, and the code says it's the upstream O2 sensor.

Hi there. If you have a code for the upstream O2 sensor then that is the most likely problem. Knowing the code would help me to be able to tell for sure what is going on. If you replaced the sensor and the same code returned then you may have used the wrong type/brand of sensor, or there may be a problem with the fuel mixture. A vacuum leak or leaking fuel injector can cause an O2 sensor code. If the sensor is new then a mechanic would typically install a computer scan tool in order to check the fuel mixture to see what is going on.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Check Engine light; upstream O2 sensor

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Driver pressed brake pedal and car started spinning

Hello. I'm glad that everyone was okay. The rotor falling apart as you described could very well cause a loss of control of your 2007 Honda S2000. When that rotor goes out, the other rotors will still be operating normally and it will...

Q: Check Engine light illuminated

Hi. A Check Engine Light that relates to a leak will usually be an EVAP leak. EVAP leaks can be very hard to find without the proper training or equipment. I suggest having a well technician use a smoke machine...

Q: Car overheated on freeway

Hello. If the car will only overheat on the freeway and not anywhere else, I suspect you may have a common civic issue, which is a failing head gasket. Head gasket repair is generally pretty expensive. But there are other...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...