Is250 Fuel Smell

james250 · August 7, 2014

Past few days I've been driving with my windows down and AC off and from time to time I was getting whiffs of fuel kind of smell. It's like the smell u get when behind a really old car that has a smelly exhaust which smells a bit like unburnt fuel. At first I was thinking it's coming from another car somewhere in the traffic. But today I started my car and was standing behind my car and i was getting this very strong smell. So it seems like the smell is coming from my exhaust. If I put my nose near the exhaust it's very strong. Never smelt this before and I always stand behind my car from time to time loading and unloading etc.

Only recent thing I did was full fuel at Tesco. I usually fill my fuel at shell or bp. But as I was in a rush I filled at Tesco but put their premium fuel in instead. About 6k miles ago I did use bg44k. Wondering if I should put another can in?

Any ideas what could be wrong.

ColinBarber · August 7, 2014

can you smell it in the engine bay?

ChumpusRex · August 7, 2014

The exhaust will smell a bit of fuel when cold, because the catalytic converter won't have warmed up; and the cat only filters out the fumes when hot. The IS250 was designed for USA Ultra-low emissions, so the catalyst is designed for very fast warm-up (but to do this, the ECU deliberately rigs the engine to run very inefficiently for the first 20 seconds or so, so that cat has burn off lots of unburned fuel)

The ECU does monitor the performance of the catalyst, and will put the emissions light on if the catalyst isn't up to par.

One possibility is a hole in the exhaust which is letting fumes out before the catalyst (or between the first catalyst and the secondary catalyst), although this too might trigger an engine light (but it depends where the hole is in relation to the sensors). It would be worth having a sniff around the car - under the bonnet, behind the front wheels, etc. to see if your nose can find a source. You are also likely to be able to hear a hole as the exhaust escapes under pressure.

Possibly it's a bad batch of fuel, but pretty unlikely.

james250 · August 8, 2014

can you smell it in the engine bay?

Nope, i cannot smell it anywhere in the engine bay or anywhere else except the back of the car

The exhaust will smell a bit of fuel when cold, because the catalytic converter won't have warmed up; and the cat only filters out the fumes when hot. The IS250 was designed for USA Ultra-low emissions, so the catalyst is designed for very fast warm-up (but to do this, the ECU deliberately rigs the engine to run very inefficiently for the first 20 seconds or so, so that cat has burn off lots of unburned fuel)

The ECU does monitor the performance of the catalyst, and will put the emissions light on if the catalyst isn't up to par.

One possibility is a hole in the exhaust which is letting fumes out before the catalyst (or between the first catalyst and the secondary catalyst), although this too might trigger an engine light (but it depends where the hole is in relation to the sensors). It would be worth having a sniff around the car - under the bonnet, behind the front wheels, etc. to see if your nose can find a source. You are also likely to be able to hear a hole as the exhaust escapes under pressure.

Possibly it's a bad batch of fuel, but pretty unlikely.

I did sniff around with my nose, and could only smell it from the back exhaust tip and it wasnt constant, it was random bursts of the smell, but each burst was quite strong smell

k111aku · August 12, 2014

I've had the exact symptoms described here.

Really confused about it. And there are no visible petrol leaks.

is200 Newbie · August 12, 2014

James

I have a problem with my O2 sensor and have been looking through a lot of web sites for info and to see where I can get replacements from.

I cant remember where I saw it (saw it mentioned on two sites or forums) There was an issue, same as yours, where the driver could smell fuel when driving - turned out, in their case, that there was a faulty sensor.

Might be worth your while looking down this route - can you have the car fault codes read to see if theres anything recorded?

ColinBarber · August 13, 2014

I would suspect a faulty upstream O2 (air/fuel ratio) sensor or fuel injector - probably the former and probably not bad enough for the engine management light to come on yet or for an error code to have been stored.

Whilst the vehicle will still drive fine you are probably wasting a bit of fuel and it will ultimately damage your cat so it is worth getting it fixed.