P0174 system too lean, bank 2. What's the cause?

ianM · 19th May 2024, 20:03

Hi all,

Apologies for the lengthy post - there's a bit of back story to this one.

Had a bit of a disaster the other day. Driving on holiday and my engine loses power completely - the revs just start dropping and suddenly I'm just coasting. Luckily just happened to be passing by a layby so pulled in, tried to restart engine, and it was dead -just turns without firing.

A quick look round the forum from said layby made it sound like the dreaded Fuel Filter Syndrome - my car being a 2002 petrol v6 - so I call out the RAC who take a look, and confirm the two part fuel filter has come apart. They screw it back together, and the car gets me where I'm going, but something still seems off, as there's a lingering smell of petrol outside the car....

I try to start the car the next morning, and although at first it won't fire, it catches when I try a second time. I put a few revs on and all is fine for a second, but suddenly the revs drop off a cliff and it keeps bottoming, going between 400-200 revs, and sounding like it's about to stall (because I guess it is). Putting my foot down does nothing.

So I have another visit from the RAC who after much drama get access to the fuel filter again, only to find one part of the rubber seal around the top of the petrol tank/fuel filter wasn't seated properly, and was half in the fuel tank itself, having been pushed too far down, leaving a direct route from the outside of the car to inside the fuel tank - which at least explains the petrol smell outside the car. In testing the fuel filter cap was still tight, he twisted the top right, left, then right, which appeared to loosen it slightly (which is exactly the opposite of what I want!)

He put it back together, we fired it up, and it at least started and kept a steadier revs - but it was running lumpy, is now backfiring at 2000 rpm, and my check engine light came on, with the error code P0174 - system too lean (left bank). I don't remember this coming on before - the first time I saw it was after this second repair.

It seems unlikely I would have ended up with two separate problems at exactly the same time, but would the RAC not managing to get the fuel filter in properly (again) really cause it to run lean one sided? Or is this something other than Fuel Filter Syndrome?

The car is currently being recovered back home via an RAC "secure compound", so I was really hoping to consult the hive mind before I get to take a proper look when I get it back.

The codes were read via my £5 ebay jobbie OBD sensor, as the RAC man's tablet couldn't get a reading at all...

19th May 2024, 20:03	#1
ianM Avid contributor Rover 75 2.5L V6 Saloon; Rover 214i Join Date: Sep 2010 Location: West Midlands Posts: 102 Thanks: 18 Thanked 1 Time in 1 Post	P0174 system too lean, bank 2. What's the cause? Hi all, Apologies for the lengthy post - there's a bit of back story to this one. Had a bit of a disaster the other day. Driving on holiday and my engine loses power completely - the revs just start dropping and suddenly I'm just coasting. Luckily just happened to be passing by a layby so pulled in, tried to restart engine, and it was dead -just turns without firing. A quick look round the forum from said layby made it sound like the dreaded Fuel Filter Syndrome - my car being a 2002 petrol v6 - so I call out the RAC who take a look, and confirm the two part fuel filter has come apart. They screw it back together, and the car gets me where I'm going, but something still seems off, as there's a lingering smell of petrol outside the car.... I try to start the car the next morning, and although at first it won't fire, it catches when I try a second time. I put a few revs on and all is fine for a second, but suddenly the revs drop off a cliff and it keeps bottoming, going between 400-200 revs, and sounding like it's about to stall (because I guess it is). Putting my foot down does nothing. So I have another visit from the RAC who after much drama get access to the fuel filter again, only to find one part of the rubber seal around the top of the petrol tank/fuel filter wasn't seated properly, and was half in the fuel tank itself, having been pushed too far down, leaving a direct route from the outside of the car to inside the fuel tank - which at least explains the petrol smell outside the car. In testing the fuel filter cap was still tight, he twisted the top right, left, then right, which appeared to loosen it slightly (which is exactly the opposite of what I want!) He put it back together, we fired it up, and it at least started and kept a steadier revs - but it was running lumpy, is now backfiring at 2000 rpm, and my check engine light came on, with the error code P0174 - system too lean (left bank). I don't remember this coming on before - the first time I saw it was after this second repair. It seems unlikely I would have ended up with two separate problems at exactly the same time, but would the RAC not managing to get the fuel filter in properly (again) really cause it to run lean one sided? Or is this something other than Fuel Filter Syndrome? The car is currently being recovered back home via an RAC "secure compound", so I was really hoping to consult the hive mind before I get to take a proper look when I get it back. The codes were read via my £5 ebay jobbie OBD sensor, as the RAC man's tablet couldn't get a reading at all... Last edited by ianM; 19th May 2024 at 21:11..