Skip the auto shop - Our mechanics make house calls

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.

A: Hi there. If you have a code for the upstre...

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?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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: How do I play a DVD through the overhead screen?

To play a DVD, simply insert a DVD into the DVD slot in the center console compartment control panel, when the overhead screen is turned on. The DVD will automatically start playing, and you can use the controls on the...

Q: I believe my alternator has gone bad, how much would it cost to fix or replace?

Prior to replacing the alternator, it has to be tested to determine if the alternator has actually failed especially in your circumstance where the check engine light (CEL) is on which light could mean that another problem, other than the...

Q: Tail lights do not turn on fuses look good

If you are not getting any tail lights in the front or back then first check fuse 32 in the under dash fuse panel and at same time check the fuse socket to see if you are getting power to...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.