2004 S60 T5M Doubled Fuel Consumption [Bad ECT] Topic is solved

grizzlyturtles · Post by **grizzlyturtles** » 19 Jul 2019, 10:05

Hey guys, going to try my luck here.

So on the weekend my car felt like it lost some power and was accelerating a bit slower than usual. I brushed it off as nothing. The next morning, when driving to work, my fuel consumption shot up to around 14-15 L/100KM. Usually, I would get around 10.8 L/100KM. This seemed fishy.

Later in the day, the average went from 14 L/100KM to 16 L/100KM driving just down my road. Now it managed to reach an all time high of 25, and would increase gradually if stuck at a stop light. Now if I drive it the fuel consumption can reach around 19 L/100km.

The car is dumping so much fuel that the oil now smells like gas badly.

So far I have cleaned the MAF and air filter, which changed nothing. I checked all the spark plugs and they all look new and clean, no excessive carbon buildup at all. The car throws no codes whatsoever, so I have no clue where to start looking.

Engine model is a B5234T3, manual transmission model is M56. Car has 136,xxxKms.

Any idea what is causing the unnecessary over fueling?

DrDan · Post by **DrDan** » 19 Jul 2019, 13:59

Maybe coolant temperature sensor
(ECT) falsely indicating cold engine?
Engine actually not warming up as it should due to thermostat stuck open causes high fuel consumption like that but does throw a code, at least if the condition persists long enough.

grizzlyturtles · Post by **grizzlyturtles** » 19 Jul 2019, 14:20

Well I haven't been driving the car due to the fact that there is gas in the oil, I've parked it since the issue started. Perhaps that's why the light hasn't come on. Would the temperature gauge in the car still work though if the sensor is broken? I know that if the thermostat is broken it will still give a reading.

This would explain why the car is running very rich I guess.

DrDan · Post by **DrDan** » 19 Jul 2019, 14:48

I suppose that if the sensor fails the way I described, the gauge would read low, as if the engine was cold, even when it's warm.

When my thermostat failed I was pointed to the problem when pulling codes. I think there was no check engine light or warning message. Did you check for fault codes using a code reader?

grizzlyturtles · Post by **grizzlyturtles** » 19 Jul 2019, 15:21

Well the gauge does reach full temp (halfway) as it always has. Not sure if what you said would still be an issue then.

I have not checked codes but my friend does have an OBD scanner that I can borrow, I'll try and see if there's any fault codes.

Post by **E Showell** » 19 Jul 2019, 15:52

I have had a bad engine coolant temperature sensor on P80s and it causes all kinds of hurt along the lines you've stated.

When were the O2 sensors last replaced?

grizzlyturtles · Post by **grizzlyturtles** » 19 Jul 2019, 16:54

As far as I know, never.

grizzlyturtles · Post by **grizzlyturtles** » 19 Jul 2019, 18:25

Just ran an OBD2 scanner and got nothing

93SCMax · Post by **93SCMax** » 20 Jul 2019, 07:34

grizzlyturtles wrote: ↑19 Jul 2019, 10:05
The car is dumping so much fuel that the oil now smells like gas badly.

Any idea what is causing the unnecessary over fueling?

You might have a stuck open or leaky injector, but I'd expect that you would see a very wet spark plug. Sounds like a cylinder is being washed down and excess fuel leaking past the rings. Fuel in the engine oil is serious.

Possibly time to pull the fuel rail?

Post by **E Showell** » 20 Jul 2019, 09:06

Plus that much unburnt fuel will toast the CAT converter before long.