Service Engine Soon light on 2000 Nissan Maxima GLE with code P0174 Car also shudders and sometimes stalls when cold idle is lower than usual around 600 rpm - what wrong?

The Service Engine Soon light on your 2000 Nissan Maxima GLE is likely illuminated due to the presence of the P0174 trouble code. This code indicates that the engine's fuel system is running lean, meaning there is more air than fuel in the combustion mixture. This can cause a number of issues, including:

- Engine shuddering or shaking, particularly at idle or under acceleration

- Engine stalling or hesitating

- Rough idling

- Reduced fuel efficiency

- Increased emissions

In addition, the lower idle speed that you have noticed (around 600 RPM) is also likely related to the P0174 code. A lean fuel mixture can cause the engine to run hotter than normal, which in turn can lead to lower idle speeds.

There are a number of possible causes for a P0174 code, including:

- Faulty oxygen sensor

- Vacuum leak

- Faulty fuel injector

- Clogged fuel filter

- Faulty fuel pressure regulator

- Exhaust gas leak

It is important to have the P0174 code diagnosed and repaired by a qualified mechanic as soon as possible to prevent further damage to your engine. The mechanic will be able to determine the root cause of the code and perform the necessary repairs to restore your car to proper operation.