Q: Check engine light - O2 sensor circuit + speed sensor circuit...

asked by on

My car started occasionally stalling out, usually when slowing down quickly for a turn lane. Last week, the check engine light came on. I assumed I needed a tune-up, so I took it to Autozone to buy spark plugs and get the OBII reading... reading said O2 Sensor, Sensor 1, Bank 1 low voltage. I went to a pull-a-part, found a 2010 Sentra and got an a/f sensor and replaced it. Check engine, still on. Took it to get another reading... Same O2 sensor code PLUS a low voltage code for the speed sensor. I really don't think I did any damage while installing the a/f sensor. Is this likely a problem with the wiring harness? Autozone guy said maybe a mouse was chewing the wires? I can't imagine that. What's my next step?

My car has 118000 miles.
My car has an automatic transmission.

Hi there. O2 sensor low voltage can be caused my a number of things. Mass air flow sensor was only one of them. It can be a bad O2 sensor, coolant temperature sensor, or wiring issue.

What should be done is a proper diagnosis for the Check Engine Light. Using a complete scanner rather than just a code reader gives a technician the opportunity to not only read trouble codes, but to read voltages for individual sensors. While a code reader tells you the relevant system that set the Check Engine Light on, but with a number of possible causes, the full scan tool allows checking of each individual cause. Having a proper diagnosis will help you have this repaired correctly without replacing parts that are not faulty.

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 - O2 sensor circuit + speed sensor circuit...

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: Q: Speedometer stops working

Depending on the type of vehicle you have and how the speedometer is actuated is going to be different. You may have a speed sensor in the transmission and run off of the out put shaft or a sensor in...

Q: Where is the Mass AirFlow (MAF) sensor located on this car? 2005 Saturn L300

Hello - the mass airflow (MAF) sensor is the black plastic cylindrical tube with an electrical harness that goes into the air filter housing on your engine air intake system. I would check for problem codes first however, as the...

Q: Gurgling noise while brake and pumping feeling in reverse

The intermittent illumination of the Check Engine Light (CEL) should be resolved by getting a CEL Diagnostic and then repairing the fault that is identified. Such a diagnostic might provides clues as to the other faults you are writing in...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...