2000 MB E430 with Code P0303

[HTSS_TR]

My 15 years old with 15x,xxx miles 2000 Mercedes E430 with 4.3L V8 engine had the code P0303 yesterday. It had the code P0300 last week, a bottle Techron concentrate seems to fix that problem.

According to engine-codes.com, possible causes:

- Faulty spark plug 3
- Clogged or faulty fuel injector 3
- Faulty ignition coil 3
- Fuel injector 3 harness is open or shorted
- Fuel injector 3 circuit poor electrical connection
- Ignition coil 3 harness is open or shorted
- Ignition coil 3 circuit poor electrical connection
- Insufficient cylinder 3 compression
- Incorrect fuel pressure
- Intake air leak

http://engine-codes.com/p0303_mercedes-benz.html

Spark plugs(16 of them) were changed 2-3 years ago at around 130-135k miles with OE Bosch platinum plugs.

Ignition coils(8) and wires(16) are original.

How do you test the ignition coils and what resistance I should test for spark plug wire ?

Also, which one is cylinder number 3 of the V8 engine ?

 

[goodtimes]

My wife had an 01 which she spent about 3k on at the dealer to fix it. It still kept throwing codes. It ran but everything would light up and said everything was wrong. I got the idea to look at the Bosch alternator voltage regulator, and found it has brushes attached to it as a unit, and they were worn down. I went to the dealer and for $120 got a new vr. No more problems. Took a little care to install but not that hard. Not saying that's it, but never know.

 

[Falken]

I'd pull the Cyl#3 plugs (X2) and examine the gap and color.

If it looks ok, I would start switching around common items to Cyl#1 INCLUDING the Cyl#3 plugs even if they look good and see if you can get all your P030X to pop up on Cyl#1.

If you can pull that off good news, cheap fixes abound.

If you can't, keep us posted!

If you get persistent problems maybe have your fuel pressure tested, if ok, maybe have your gas tank completely cleaned out.

I'd change the fuel filter for good measure.

BUT, if Cyl#3 is PERSISTENT, maybe it is the injector, a stuck ring, carbon, or the compression is low. We are starting to get pricey now...

 

[HerrStig]

Originally Posted By: goodtimes
My wife had an 01 which she spent about 3k on at the dealer to fix it. It still kept throwing codes. It ran but everything would light up and said everything was wrong. I got the idea to look at the Bosch alternator voltage regulator, and found it has brushes attached to it as a unit, and they were worn down. I went to the dealer and for $120 got a new vr. No more problems. Took a little care to install but not that hard. Not saying that's it, but never know.
Those Hella regulators are now made in China and cost about 22 bucks on the internet, compared to the one hundred and change from a dealer. Just put oone in my son's 633CSI. The, ahhh ..."inferior" Japanese Denso alternator comes with replacable brushes.

 

[HTSS_TR]

The problem is which one is cylinder number 3 of the MB M113 engine ?

 

[Jetronic]

could be the third cilinder in the firing order... just to confuse you more...

15 yearold cars however are not likely to detect cilinder misfires unless there's an electrical fault in the ignition system. I'd swap coils (coil on plug I'd imagine) between banks and see if the fault moves.

 

[Trav]

Originally Posted By: HTSS_TR
The problem is which one is cylinder number 3 of the MB M113 engine ?

 

[HTSS_TR]

Originally Posted By: Trav
Originally Posted By: HTSS_TR
The problem is which one is cylinder number 3 of the MB M113 engine ?

Thanks Trav. I cleared the code yesterday and it didn't come back yet. The engine is running okay now.

I will buy 2 OE Bosch spark plugs(2 plugs per cylinder), 2 plug wires. If the code P0303 comes back I will replace plugs and wires first, if these parts don't fix the problem then will replace the coil.

 

[Falken]

If possible get the correct length plug wire if it isn't COP to have the required resistance value.

Not sure if it is that important...

 

[HTSS_TR]

I will only buy 16 OE plug wires(made by Bosch). It's a little expensive but I hope that it will lasted another 100-150k miles.

So far the code P0303 didn't come back, hope to stay that way. But I'm looking to buy 16 spark plugs for it, and possibly will checke the resistance for all plug wires when I change spark plugs.