How To Test The Oxygen Sensors (Chrysler 2.0L, 2.4L)

By: Abraham Torres-Arredondo
Created: 23 July 2011
Updated: 24 August 2025
Articl Id: 12

This article will show you how to test the upstream oxygen sensor (O2S11) on your 2.0L or 2.4L Chrysler car or mini-van.

The test can be accomplish in a few easy steps and you'll be able to say, 'YES, the O2 sensor is bad or NO, it's OK' before you spend the money and replace it.

Contents of this tutorial:

Important Suggestions And Tips.
Symptoms Of A Bad Oxygen Sensor.
Oxygen Sensor Basics.
O2 SENSOR TEST: Inducing A Rich Condition.
Oxygen Sensor Codes Keep Coming Back.
More Test Articles.

Important Suggestions And Tips

TIP 1: I've designed this article so that you can use a generic scan tool. You don't need the Chrysler factory scan tool or an expensive professional technician level scan tool to follow the test procedures in this article (Don't have a scan tool? Need a scan tool? Check out my recommendation: Actron CP9580 Scan Tool).

TIP 2: This is an on-car test of the oxygen sensor on your Chrysler 2.0L, 2.4L vehicle. So you'll not be removing it to test it.

Symptoms Of A Bad Oxygen Sensor

The effects of a bad oxygen sensor can be very subtle since they usually do not cause serious drive-ability problems. Here are the most common symptoms:

The check engine light (CEL) will be illuminated on your instrument cluster.
The diagnostic trouble codes lighting up the CEL usually are:
- P0131 Upstream Heated Oxygen Sensor (O2S11) Circuit Out Of Range Low Voltage (Bank 1).
- P0133 Upstream Heated Oxygen Sensor (O2S11) Circuit Slow Response (Bank 1).
Really bad gas mileage.
Won't pass state mandated emission testing.

Oxygen Sensor Basics

In a nutshell, the job of the pre-catalytic converter oxygen sensor is to report back to the PCM that it is either injecting too much fuel (known as a Rich condition), or that it is not injecting enough (known as a Lean condition).

Depending on what the O2 sensor is reporting, the PCM will adjust the amount of fuel it's injecting into the engine.

Here are some more specifics:

If too much fuel is being injected into the engine, the oxygen sensor produces a voltage above 0.500 Volts. This voltage can go as high as 0.900 to 1.0 Volt.

Too much fuel means that the air fuel mixture is rich and once the PCM knows this, via the O2 sensor, it starts to inject less.
As the PCM starts to inject less fuel, it may go too far and not inject enough. Here again the O2 sensor saves the day by reporting a voltage that can go as low as 0.050 to 0.100 Volts.

Too little fuel means that the air/fuel mixture is too lean and the PCM starts to inject more.
This process (of adjusting the amount of fuel being injected) by the PCM, goes on the entire time the engine is running (and if the O2 sensor is working correctly).
All of these oxygen sensor voltages changes can be easily observed with a scan tool in live data mode, and this is how I'm gonna' show you how to test them.
A correctly working O2 sensor will produce a voltage that will switch between a lean and rich condition several times every few seconds.

So, if the voltage output of the O2 sensor stays fixed (when testing it) then you can conclude that the O2 sensor has failed.

O2 SENSOR TEST: Inducing A Rich Condition

To test the oxygen sensor (O2S11), the very first thing you'll do is to induce a Rich condition.

This can easily be done by spraying a little carburetor cleaner into the engine while it's running. My preferred method is to spray carb spray into a vacuum hose.

Once the carb spray hits the engine cylinders, you'll get an instant Rich condition which will make the O2 sensor respond by producing its maximum voltage (0.900 Volts +) and you'll be able to see this on your scan tool (in Live Data mode).

Alright, this is what you'll need to do:

1
Start your vehicle and let it idle for about 15 minutes, since you need a warmed up engine to get the O2 sensor to activate.
2
Connect your scan tool and get to its Live Data mode.
3
Once you're in Live Data mode, scroll down to the PID that's labeled O2S11.

This PID (parameter ID) will show you the oxygen sensor voltage activity.
4
The voltage numbers of the O2 sensor moving between 0.100 and 0.900 Volts constantly.

If the voltage value stays fixed, don't worry about this yet -continue to the next step.
5
With the engine running, spray a little carburetor cleaner into a vacuum hose (that has engine vacuum) while you observe your scan tool's display screen.

You're not going to be able to spray carb cleaner into the throttle body bore as the engine is running, because if you were to do this, the engine will die as soon as you disconnect the air duct from it (to spray into it).

NOTE: If you spray too much, the engine will stall. If this happens to you, just restart the engine and repeat the step and spray less carb cleaner spray.
6
You should see the voltage numbers of O2S11 immediately spike to 0.800 to 0.900 Volts.

And as long as you're spraying, these voltage number should stay there.
7
When you stop spraying, the O2 sensor values should come down and within a few seconds, they should start oscillating between 0.100 Volts to 0.900 Volts. If they don't don't worry about it yet.

OK, the test is done, let's take a look at what your test results mean:

TEST RESULT 1: O2S11 voltage numbers spiked to 0.900 Volts when you sprayed carb spray into the vacuum hose. This tells you that the oxygen sensor is OK at this point in time. It does not need to be replaced, since whatever's causing the PCM to think it's fried is something else.

For more info on this, go to the section: Oxygen Sensor Codes Keep Coming Back.

TEST RESULT 2: O2S11 voltage numbers DID NOT spike to 0.900 Volts when you sprayed carb spray into the vacuum hose. This confirms that Bank 1 Oxygen Sensor 1 is no longer working. You can replace the oxygen sensor.

Oxygen Sensor Codes Keep Coming Back

So you tested the oxygen sensor and they tested good or you have already replace one or both and yet the PCM keeps accusing them as being bad (which also means that the check engine light is back on).

When this happens, it's usually due to either a Rich condition or Lean condition that's being caused by some other component on the engine.

What sucks about this, is that whatever is causing the Rich or Lean condition is not present all of the time (specially when you're conducting the tests). This happens quite a bit. The strategy here is to wait a few days for the condition (that's causing the O2 sensor issues) to get worse. When this occurs you'll be able to test it and solve it.