Skip the auto shop - Our mechanics make house calls

Q: Check Engine Light is on and Autozone read: Trouble Code P0138 O2 Sensor Bank 1 Sensor 2 High Voltage

asked by on

I bought this car used about a week and a half ago. The first week it seemed fine with no check engine light but it needed some work. It had the wrong coolant in it, so I had the system flushed and refilled. It was after having this done the check engine light came on the first time. I got a new gas cap and the light went off for a little while, then it came back on and I noticed the air filter was extremely dirty and I changed that. After changing the air filter the light then went off again and I took it for a drive and it performed extremely well; I was surprised at how well it ran and thought I had fixed it. The very next day, though, the check engine light came on again and the car began to run very rough and sluggishly. It has since stayed on and not gone back off. The second time the light came on I also noticed a slight surge of the tachometer. What could this be? Thank you, Jamie.

My car has 135000 miles.
My car has an automatic transmission.

A: Hello. If it has a code for an oxygen senso...

Hello. If it has a code for an oxygen sensor then that may be the issue. The thing about the oxygen sensors though is that they can give a false reading if there is something else going on with the engine.

I usually install a scan tool and see how the sensor is reading as that can tell me if the sensor is failing or if there is another issue with it. If the sensor looks like it is reading improperly then I replace it.

If it seems to be fine then it may be a weak fuel pump, or a misfire issue. It can also be another sensor that is causing it to read like this.

If you are planning on having this rough running condition checked out, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose why it is running rough and why the engine light is 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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: My car heater will blow hot air and drive fine for 30 minutes then my heater blows cold air and my car overheats

Hello. With the recent repairs that have been made to the vehicle, there is only one main heating component that you have not looked into. This would be your heater core. The heater core is responsible for pulling hot coolant...

Q: How do I return the rear seats to their upright position?

When you are not using the rear seats for added storage space, you should return them to their upright position. Doing so takes only a few steps: 1. Pull both sides of the seat up into their upright position. 2....

Q: My SUV is running hard and has the Diagnostic Trouble Code P0016

Hi and thanks for contacting Your Mechanic. The code P0016 is for the crankshaft position sensor. Check the wiring harness to the sensor that is located on the bottom of the engine by the crankshaft pulley. Check for voltage and...

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...
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...