Codes for OBD II PO174

I have a 96 Grand Marquis. It has 93,000 original miles on it . The check engine light came on so I used my code reader and the code P0174 - left bank to lean. What does this mean ? I hav'nt changed the plugs yet. I just bought the car last week and the light was on then. Also are the spark plugs screwed into the PLASTIC intake or are they screwed into metal block ? Thanks for your help. PS overall, are these good cars ? Should I use Amsoil universal ATF when I change the trans fluide ? Thanks again, Dan.

Try cleaning the MAF sensor and see if the light comes off. The plugs are screwed into the heads. Use Mercon V in the transmission only..................!!!


I have a 96 Grand Marquis. It has 93,000 original miles on it . The check engine light came on so I used my code reader and the code P0174 - left bank to lean. What does this mean ? I hav'nt changed the plugs yet. I just bought the car last week and the light was on then. Also are the spark plugs screwed into the PLASTIC intake or are they screwed into metal block ? Thanks for your help. PS overall, are these good cars ? Should I use Amsoil universal ATF when I change the trans fluide ? Thanks again, Dan.

What do I use to clean the MAF sensor ? Also ther is a box in the trunk with a red button to push. What is it for and why , when , and how would I use it. Thanks Dan.

brake or carb cleaner will do, as for the box i have no idea.


What do I use to clean the MAF sensor ? Also ther is a box in the trunk with a red button to push. What is it for and why , when , and how would I use it. Thanks Dan.

There is a special spray for the MAF. Ask for it at your local auto parts store. I would NOT use Carb, Brake or other cleaners. The connectors are VERY finicky and the wrong type of cleaner will ruin them. Takes a special bit to take the switch out. Can get one at the parts store. Be certain to NOT touch the filliments/connectors under the switch before/during/after spraying them. DON'T use cotton or any material to "rub/clean" them. Use the Special spray and SPRAY THEM ONLY!! When properly cleaned they will turn from black or dark gray (or perhaps brown) to a bright silver.

As for the box in the trunk with the Red Button it is an Inertia Switch and it's function is to shut off the fuel supply in case of a crash. If it ever "trips" on it's own the car will not start and you need to only push the red button to reset it. Sort of like a circuit breaker. MB