Have You Put Petrol in a Diesel Mercedes CLS?
We'd ask you to leave your motor off when you have put petrol in a diesel Mercedes CLS and not started it yet, and that counts for shifting it off the forecourt too. With the motor left off, the petrol stays where it is in the tank, and in most cases a fuel drain is all your CLS needs.
Petrol in Diesel empties wrongly fuelled cars on the spot, and the Mercedes CLS can stay on the forecourt or wherever it has stopped. Call us before anything else then let us take you through it, rather than attempting anything on your own.
First steps for petrol in a diesel CLS
- Don't start the motor, even though a diesel CLS will generally run with petrol inside your tank. It may seem fine for a time, and that's how drivers often drive away without noticing anything is amiss.
- Keep the ignition off as well. On many diesels switching it on is enough to start the fuel pump priming, which draws fuel out of your tank to your injectors.
- Diluting the petrol by filling up with diesel doesn't help. It just adds to the contaminated fuel to be drained from a tank that holds up to 80 litres in the CLS, and super unleaded counts as petrol here as well.
- Ask the forecourt attendants if the vehicle is blocking a pump. They generally help push it clear once it's in neutral.
- When the badging shows the precise version, for example the CLS 320 CDI, mention it when you phone 0333 366 0103. Let us know as well which CLS you have and where it is, about how much petrol was put in and whether the engine has run.
Driving on wrong fuel in your Mercedes CLS
The engine is not affected by wrong fuel in your Mercedes CLS until it is pulled from your tank, and starting the engine is what draws it out. The high-pressure pump and your injectors on a diesel motor are oiled by your fuel passing through them. Petrol dilutes the diesel and washes that protection away, and that is why it is driving any distance on the mixture that can do damage.
Look for somewhere safe to stop then turn off, when the CLS has already been on the road. It can still be sorted out, with your tank emptied and the pipes and filter rinsed until every trace of the contaminated fuel has gone. When it's caught soon and flushed out thoroughly, long-term damage is very unusual.
The CLS 350 CDI 4Matic is no different in this from any other version of the CLS.
Your Mercedes CLS fuel tank capacity, version by version
The size of your tank counts because the danger depends on what proportion of your fuel in it is petrol, so the same couple of litres are a bigger problem if the tank was nearly empty when you fuelled up.
Tank sizes on the Mercedes CLS go from 59 to 80 litres according to which version it is.
Our data place the largest tank in the CLS 350 CDI and the smallest in the CLS 250 CDI.
For the CLS 350 CDI Shooting Brake 4Matic, the tank size is 80 litres.
| Version | Fuel tank |
|---|---|
| Mercedes CLS 250 CDI | 59 litres |
| Mercedes CLS 250 CDI Shooting Brake | 59 litres |
| Mercedes CLS 320 CDI | 80 litres |
| Mercedes CLS 350 CDI | 80 litres |
| Mercedes CLS 350 CDI 4Matic | 59 litres |
| Mercedes CLS 350 CDI Shooting Brake | 80 litres |
| Mercedes CLS 350 CDI Shooting Brake 4Matic | 80 litres |
What diesel version of the CLS do you drive?
It helps us to have the version when you ring, and it is generally on a badge at the back of the vehicle.
On the diesel CLS, the badging used is CDI.
Put AdBlue in a diesel Mercedes CLS?
To clean up their exhaust, some diesel vehicles use AdBlue, a mix of water and urea that is put in its own tank through its own filler. Putting AdBlue in the wrong filler leaves you with AdBlue in a diesel Mercedes CLS, so do not touch the key, not even to move it.
The fuel pump gets no lubrication whatsoever from AdBlue, which is largely water and won't burn. It will not blend with diesel either, and drops to the base of the tank, the very place your pump draws from, so a tank holding up to 80 litres won't dilute it.
Even a little is drawn into your fuel line. Inside the fuel system the water evaporates and lets the urea crystallise, in your filter and injectors among other places, where it eats into the metalwork it sits against.
Where your CLS has an AdBlue filler, it could well lie alongside your diesel filler under the same cover, as it does on many motors. You can normally tell the AdBlue lid by its blue shade and the much narrower nozzle it takes.
How a fuel drain on your Mercedes CLS works
We do a fuel drain on your Mercedes CLS where the vehicle sits, and it doesn't need to be taken to a garage. We begin by checking what was put in and whether the engine has been run, then drain your tank, which on the CLS holds up to 80 litres. Next we flush the fuel lines and the fuel filter and refill with fresh diesel, and the fuel system is primed before we start the car.
For the CLS 350 CDI Shooting Brake, the tank is 80 litres.
You are free to take the CLS away once we have finished, running on clean diesel.
What AdBlue removal from a diesel Mercedes CLS involves
AdBlue removal from a diesel Mercedes CLS follows the same stages as draining petrol. As AdBlue doesn't mix in but collects at the bottom of the tank, running the CLS on it can leave deposits in the lines. Those get cleared through as well, and the filter is swapped if it needs it.
Here, AdBlue removal means taking AdBlue back out of a diesel tank it was put into through the wrong filler. Switching off or removing the AdBlue system on a vehicle is not what it means.
The cost of a fuel drain on the Mercedes CLS
We don't publish a fixed price, as this work changes from one job to the next. These are the biggest factors that change it:
- whether anyone has started or driven the CLS, the thing that matters most
- the volume put in, weighed against the capacity of your tank
- whether it was AdBlue rather than petrol
- whether our van can easily and safely reach the CLS where it stands
The CLS 250 CDI Shooting Brake takes 59 litres when it is full, by comparison.
If you call with those details we can tell you what the work is likely to involve.
Petrol in a diesel Mercedes CLS: questions
The Mercedes CLS fuel tank capacity: how many litres?
It depends on the variant, from 59 to 80 litres, and every one is shown in the table above.
Is it OK to add diesel after just a little petrol in my CLS?
It isn't something we'd advise, because adding diesel does nothing to remove that petrol. It just reduces its share, and the petrol is still in your system once you drive off. A fuel drain gets all of that out, and with a small amount that is generally all the CLS needs.
Must my CLS go to the Mercedes dealer?
No, we come to it. Your CLS is drained and cleaned where it has stopped, by an independent business with no link to Mercedes or any dealer.
Does the version of my CLS matter?
It helps us to know which one you have when you ring, since we hold figures for 7 diesel variants of the CLS.
Does my insurance policy cover wrong fuel in my Mercedes CLS?
We'll still come out to drain it for you, either way. Check your policy anyway, as not every policy has misfuelling cover.
What should I do if my CLS got diesel in its AdBlue tank?
In that case, too, leave your key out of the ignition. The AdBlue system will need emptying, and when the car is driven like that, it'll most likely show a warning and enter limp mode. Which tank your diesel was put in is worth telling us when you phone.
What should I do if I have already driven my CLS?
Look for a safe spot to pull over, then switch your engine off and keep the car that way till we arrive. Spotting it this early means lasting damage is very rare, plus we drain and clean your fuel system wherever you happen to be.