Low fuel consumption and codes P0300, P0301, P0302, P0304 and P0174?

Hi,

The P0174 indicates a lean fuel mixture on bank 2. Interestingly, the misfire codes you have are for bank 1 other than the P0300 which is a random misfire.

A lean fuel mixture can be the result of several things. For example, plugged fuel injectors, an exhaust leak on bank 2 before the catalytic converter, faulty oxygen sensors, a weak fuel pump or faulty regulator, or even the ECM. As far as the fuel pump is concerned, in most cases, it will not be limited to only one side of the engine.

So, in this case, here is where I would start. First, check to see if you hear an exhaust leak at the engine exhaust manifold (one side only). If you hear nothing, then I need you to check for engine vacuum leaks.

Here is a link that explains how that is done:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, if you have or have access to a live data scan tool, let me know what the short-term fuel trims are with the engine at operating temperature.

Let me know if you have questions and what you find.

Take care,

Joe

Hi,

Thanks for the update. I'm glad to hear the problem is resolved.

As far as the sensors being the same, it is likely due to the converter itself. If the catalytic converter is not functioning properly, it won't effectively reduce emissions. This could lead to similar oxygen sensor readings before and after the catalytic converter.

If it is running properly and there are no codes, drive it. If the converter is faulty, it will eventually set a P0420 or P0421. If it doesn't, I wouldn't worry about it.

Let me know if anything happens.

Joe