I have 2009 C204
I recently noticed that my gas is usually using a lot than normal
I filled up petrol last week and within a week, its already used like almost 1/4 of the tank where I have travelled approx no less than 100KM where half is on highway so the fuel consumption would have been lower so I certainly wouldn't expect that it would used 1/4 tank of fuel

Yesterday I filled up again to full again as to test it and since I filled up last week, according to the docket that I paid, it was like 23 litres and I think this is very abnormal given I only travelled around 100km last week, no?
It was originally around 800km (according to the steering wheel fuel consumption on the dashboard and decided to monitor )
Yesterday and today I went back and forth in my local around several times around 10km in total
I noticed that even when I drive, the KM doesn't fluctuate like it normally does but instead, it drops consistently to like 1KM per like 15 seconds despite I tried to drive slowly and not press too hard on brake etc
Now i see my fuel consumption is 570km
I only recall last week there was a RED error sign of like tyres pressure or something my on dashboard
But when I went to the gas station and pumped, it was fine and normal, it didn't have anything wrong and I thought it might be a glitch or something
I am not sure if that was the culprit or otherwise, I can't think why this is decreasing pretty rapidly

Anyone knows what might be problem?

PS: The weather has been very hot these few days averaging around 30 degrees, not sure if that is the issue as I park in the driveway but even so, I haven't had any problems like that before, no/

 

Hi gobear, I hope this will help.The rapid decrease in fuel economy and unusual fuel consumption on your 2009 C204 could indicate several potential issues:

1. Fuel System Problems: Check for any leaks in the fuel lines, fuel injectors, or the fuel tank itself. A leak could lead to a significant loss of fuel.
   
2. Tire Pressure Warning: The warning you saw regarding tire pressure might not directly affect fuel consumption, but it's worth ensuring that your tire pressure is within the recommended range. Under-inflated tires can cause increased rolling resistance, which might result in reduced fuel efficiency.
   
3. Engine Issues: If your car's engine is not running optimally, it could consume more fuel than usual. Faulty sensors, air intake issues, or problems with the engine's management system might cause inefficient combustion.
   
4. Driving Habits: Aggressive driving, constant acceleration, and sudden braking can negatively impact fuel consumption.
   

Given the symptoms, using a diagnostic scanner like the Youcanic scanner could help retrieve any fault codes stored in the car's system. These codes might pinpoint specific issues with the fuel system, engine, or other components that could be contributing to the increased fuel consumption. If no clear cause is identified, consulting with a qualified mechanic or technician might be necessary for a thorough inspection and diagnosis.