The oxygen (O2) sensor measures the oxygen content in the exhaust stream. It also sends rich and lean signals to the powertrain control module (PCM) so that the engine computer can fine-tune the air-fuel mixture during its closed-loop operation.
If the upstream O2 sensor (red arrow) notices that the air-fuel mixture is too rich, it will send a signal to the PCM, and on-board (OBD) diagnostics will log a P0175 code.
Diagnostic trouble code (DTC) P0175 stands for “Engine Too Rich (Bank 2).”
This code usually applies to V6 or V8 engines because they have two banks compared to four-cylinder engines that only have one.
When this code is set, the PCM can no longer adjust the air-fuel mixture automatically.
A rich air-fuel mixture means the exhaust contains very little oxygen, causing the PCM to reduce fuel delivery. The scan tool datastream will show this as negative long term fuel trim.
It should be noted that the oxygen sensor is designed to sense oxygen, not fuel. Whenever any cylinder misfires due to spark or compression, the unburned fuel in the exhaust stream and the oxygen that didn’t unite with that fuel will both pass the O2 sensor. However, all the sensor will see is the oxygen. What that means is that raw fuel from a misfiring cylinder won’t be detected for that reason. But on a misfiring cylinder, most modern ECM/PCMs will kill the injector on that cylinder to prevent damage to the catalytic converter.
Whenever any cylinder misfires due to spark or compression, the unburned fuel in the exhaust stream and the oxygen that didn’t unite with that fuel will both pass the O2 sensor.
– Richard McCuistian, ASE Certified Master Automobile Technician
If the fuel mixture becomes “too rich,” this means that the fuel trim is ranging anywhere between -15 to -30%.
The O2 sensor isn’t a usual suspect for this kind of issue because the PCM validates its readings before logging a code. If the O2 sensor passes its test and the air-fuel mixture is still too rich, the PCM will log a P0175 code.
Note: The definition of code P0175 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
P0175 is a generic powertrain code that can be logged from one vehicle to another. However, keep in mind that the steps for diagnosis and repair can vary, depending on make-model specifications.
Diagnosing this trouble code typically requires a few tools and conducting a thorough visual inspection of the affected system. If you’re not familiar with diagnosing trouble codes, it’s best to bring your vehicle to the nearest repair shop and have a trusted professional check it for you instead.
But if you’ve had some experience in dealing with DTCs before, then you can go ahead and do it yourself.
Code P0175 is a generic code that various makes and models can log, so there’s no singular, universal fix for it.
The processes required to repair your vehicle may vary depending on its make and model. For example, the repair procedures for a P0175 code in a Chevy may differ from those needed for a P0175 in a Ford.
With this in mind, if you’re unfamiliar with the processes required to fix a code P0175 error, you have two options.
If you don’t trust yourself to carry out repairs, consider bringing your vehicle to a licensed mechanic. You’ll spend more money this way than doing it yourself, but you can rest assured that the trouble code will be resolved.
Because you’re paying for both the replacement input/turbine speed sensor and the labor cost, getting a professional to carry out repairs could cost you a lot of money. Expect to spend around $100 to $300 for a complete fix.
Because there’s no universal catch-all fix for the P0175 code, you might need to try different fixes to ensure your turbine speed sensor will work without any issues.
There are two primary fixes worth trying. The first is to replace the turbine speed sensor of your vehicle entirely, and the second is to replace the torque converter.
Here are the steps to replace the turbine speed sensor.
If you want to replace your vehicle’s torque converter, follow these steps.
Dealing with the P0175 code can be challenging. Fortunately, you can easily address this issue by getting replacement parts here at CarParts.com.
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