I have a 1998 E 300 TD, I accidentally filled it with gas and started driving it down the road and realized what happened. I had it towed and drained and filled with fresh diesel. I replaced the fuel filter but it is still rough at start-up. Once it warms up it runs fine.

The check engine light was on so I took it to auto-zone and had them scan it and it. The code came back as "glow plug circuit A". Does anyone know what to do and where to go from here?

Thanks.

 

How do I know which one? Does circuit A represent a specific glow plug? Someone told me it could be a relay, is there any truth top that?

 

Engine cold, glow plugs cold, check each one with an ohm meter. The reading (at least for the older cars) is .8 ohms plus or minus .1 for a good glow plug. Higher or lower indicates a bad glow plug.

 

This is the main problem with the w210 diesels. Their fuel filter is very sensitive so the diesel fuel needs to be clean. You just have to make sure your car has the right kind and brand of diesel

 

Oldrebuitdodge did not say that you Pull the Connector that goes to the Glow Plugs off of the Glow Plug Relay to check them with an Ohm Meter.

If you have a Cheap Ohm Meter you need to put the Probes together tightly. If you get any resistance reading you need to subtract that from the Ohm Reading you get from the Glow Plugs.
If you have a High Quality Meter when you put the Probes together you will show no resistance and you don't need to do any subtraction. What you see on the Meter is the actual reading.

This is not a recommendation to buy parts from this site but under Glow Plug Repair the Diesel Giant Website has a Pictorial on how to test the Glow Plugs with the Volt/Ohm Meter/Multimeter.

Concerning the Glow Plug System in general when you have a Problem with the Glow Plugs the problem is most often caused by the Glow Plugs.
The Glow Plug Relays do go bad once in a while or the Fuse on the Relay burns or cracks. When that happens none of the Glow Plugs are going to work and you should have more difficulty starting and the Engine may also run rough.