Q: Q: O2 sensors

asked by on

I have a Toyota 4 runner, o2 sensors, #1 both banks are reading 3.25+ volts, would the sensors be bad or should I start looking father upstream? MAF, etc?

My car has 111000 miles.
My car has an automatic transmission.

Oxygen sensors don’t work in that voltage range. Oxygen sensors range from .1 to .9 volts. When the vehicle is running normal the sensor ranges between .4 to .6 volts. The O2 voltage should change constantly going above and below .5, these are called cross counts. A voltage reading stuck above .5 volts is considered rich in fuel, a reading stuck below .5 is considered lean in fuel.

Rich conditions can be caused by many things like leaking injectors, or a cylinder not working properly for example. Lean conditions are usually caused by vacuum leaks.

While I’m not sure what reading you’re looking at, I am guessing that it is possibly the fuel trim. I suggest seeking help from a qualified mechanic to help you correctly identify your issue and replace your oxygen sensors if needed.

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. Q: O2 sensors

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: ASD relay not activating

Hello. If you require an accurate wiring diagram you will be able to find one in the vehicle's service manual, or a quality repair manual. You may also be able to acquire the diagrams through a dealership or shop, or...

Q: After replacing my brake pads sway bar link and battery terminals my car won't urn on and shifter is loose asked by Yashira G on O

If the shifter is loose, such could implicate the neutral start safety switch thus explaining the no start. Try "manipulating" the shift level when in park while turning the key and see if that makes any difference. With a fully...

Q: replaced power steering pump now res overflows when cap is put on

Anytime you replace the pump you will get air in the fluid and will need to let the engine idle for a few minutes and then let it sit with engine off for 5 minutes and repeat process until all...

Related articles

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...
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...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...