P1153 is not a very common diagnostic trouble code. It can have different meanings depending on the manufacturer in question. However, for the purposes of this article, it means:
P1153:Insufficient HO2S Switching (Bank 2, Sensor 1)
This is the most common meaning of this code and applies to vehicles manufactured by:
- Honda (Acura, Honda)
- General Motors (Cadillac, Buick, Chevrolet, GMC, Isuzu, Saturn, Hummer, Pontiac)
As long as your scanner confirms that the code is Heated Oxygen Sensor Underswitching, you can continue.
In the standard definition of P1153, there are three separate sections. HO2S, Insufficient switching, and Bank 2 Sensor 1.
Although an exhaust system may have many oxygen sensors, the first in line is the most important for measuring the air/fuel ratio and keeping the engine running efficiently.
As mentioned, your engine computer (known as ECM or PCM) controls the air-fuel ratio through the heated oxygen sensor.
It will monitor the oxygen sensors in a closed loop for 90 seconds to determine if there is anything wrong with them. It does this by counting the number of times the oxygen sensors switch between rich and lean cycles.
When there is an insufficient number of switches between rich/free and lean/rich, the computer will output P1153.
Bank 2 Sensor 1
Determining where the bank 2 1 sensor is is not a challenge on four-cylinder and inline-six engines. Just look at the cylinder head and find the oxygen sensor closest to it. That is sensor 1. Since there is only one cylinder head, there is only one bank.
P1153 can ONLY appear on engines with two banks. So you will have to determine which side of the engine is bank 2
Although it is annoying to have to find bank 2, having two banks is nice as it means we can use the “swap test” to diagnose P1153 later.
Now that we know what P1153 means and how to find the oxygen sensor, we can start diagnosing it in earnest.
Most of the time, the check engine light is the only symptom you will experience with P1153. Although it is not unheard of for a vehicle to experience:
- Sudden slowdown
- Power loss
- black exhaust pipe
Causes and Diagnosis
Here is a pretty solid procedure for diagnosing a bad oxygen sensor. If you are not good with a code scanner, start with section 3, swap test.
1. Capture short- and long-term fuel trim values
If you have access to a scan tool, you can use it to capture short- and long-term fuel trim values. You will need to make sure the engine has warmed up before doing this.
Doing this will help you determine if the O2 sensor is working within specifications by looking under the hood. You will have to compare the values you capture with your tool with the values specified by the manufacturer.
While this isn’t a skill most DIY mechanics have, the concept is simple, and you can learn enough to use fuel trim to your advantage by watching this 11-minute video (it’s worth it)
2. Check the wiring harness on the O2 sensor
The bank two oxygen sensor has a hard life. It’s right there in the hot exhaust; You also have to deal with a lot of engine vibrations. The sensor wiring harness will fail more than almost any other wiring in the car.
Check if the wiring is burned or frayed. Make sure the wiring connecting to the sensor is tight and not damaged. You can do it quickly with a flashlight. You can usually see this oxygen sensor without having to take anything apart.
You can use a multimeter to determine if there is a short or open circuit. This article can make you an expert in the field in no time.
3. Swap test (only V6 and V8 optional)
Since you have a V-8 or V6 engine, you can do something called a swap test. Basically, it involves removing the bank one oxygen sensor (B1S1) and replacing it with the bank two sensor (B2S1).
Here’s how to do the swap test:
- First, clear the DTC codes with your scanner.
- Swap the O2 sensor from Bank 2 with the one from Bank 1. They will be on or just after the exhaust manifold, on each side of the engine.
- Run the engine until the check engine light comes on again.
- If the code changes to P1133 (indicating that the bank 1 O2 sensor is not switching enough), that is proof that you need a new O2 sensor.
- If the code is still P1153, you will need to continue with the diagnosis, knowing that both O2 sensors are working fine.
4. Exhaust/Vacuum Leaks
Often, a worn or brittle vacuum line allows unmetered air into the engine. When this occurs, a fuel shortage condition is created.
You can check for a vacuum leak around the vacuum lines and intake manifold. A common method is to spray carburetor cleaners around the intake/vacuum passages. When the point is found, the engine will rev up without needing to accelerate.
Obviously, carburetor cleaner is very flammable. So be careful. Make sure you have a form of fire suppression at your disposal
An exhaust leak can redirect gases that are supposed to pass over the O2 sensor. This can leave you with a flat curve, which can trigger P1153.
A faulty oxygen sensor is the most common reason why you will encounter P1153. However, there may be other issues causing this code as well. Good luck repairing your vehicle!