Skip the auto shop - Our mechanics make house calls

Q: o2 sensor reads 0 volts.

asked by on

I have a 2000 Ford Mustang v6 3.8L with a P0122, but the code isn't the main issue. The freeze frame data shows that the B1S2 oxygen sensor reads 0 volts.

To verify the o2 sensor works, I switched the two downstream sensors. I still have the same problem. The problem didn't move with the sensor.

To verify the wiring, I plugged the B1S2 harness into the B2S2 o2 sensor and it worked plugged into the other side of the car.

So, with the sensor and wiring harness verified, I'm forces to believe that the 0 volts is accurate. Could it be that all three cylinders on bank1 are misfiring resulting in no exhaust and 0 volts measured by the o2 sensor?

The freeze frame data shows 0 volts but when I graph the o2 sensor, it shows between .02 and .04.

The car idles rough. It's also rough when I press the accelerator while idling. I don't notice it when I drive it.

NOTE: The left and right exhaust manifolds and the Y-exhaust pipe were replaced last month due to a previous P0171 code.

A: You may need to look at the code P0122 sinc...

You may need to look at the code P0122 since it pertains to the throttle position sensor and this can affect all the drive symptoms you are having. The O2 sensor readings seem to be normal and you are not getting any O2 sensor codes. Your reading of between .2 and .4 volts shows that the converter is doing its job and you have high O2 in the exhaust flow. This is a common and normal reading. When the catalyst is new you may not see the O2 sensor go above .45 volts but as a catalyst ages the sensor will switch more often above the .45 volts until it cannot clean the exhaust anymore. I'd suggest getting some help with a certified technician, such as one from YourMechanic, they will help you diagnose your Check Engine Light further and help you fix it accordingly.

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・Save up to 30%

Get a quote

What others are asking

Q: Check Engine Light is on - 2012 Nissan Xterra

Anytime a code is stored, it will stay stored and the Check Engine Light will stay on until the ECM memory is cleared. If the problem is fixed, then the light and code should not come back. Many times a...

Q: My car is shaking.

Hello. the Diagnostic Trouble Codes would have to be retrieved to begin the diagnosis. Unless the shop retrieved all codes and performed a diagnosis and tested the coils (there are six of them on your engine), what they have told...

Q: What is a Eco oxygen sender and does it need replaced and cost

Hello. From your description it sounds to me like you are referring to the vehicle's oxygen sensor. Your vehicle is equipped with multiple oxygen sensors that are responsible for detecting the vehicle's air-fuel ratio. The sensors send the air-fuel ratio...

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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...