W164: P300, P301, P304 after oil + air filter- did new spark plugs- will codes reset?
Thread Starter
Junior Member
Joined: Mar 2013
Posts: 15
Likes: 0
2010 ML350 W164
W164: P300, P301, P304 after oil + air filter- did new spark plugs- will codes reset?
Hello, I could really use some help here.
I changed my oil and engine air filter at about 140,000 miles on a daily 2010 ML350. Trying to be as economical as possible here, after doing the changes drove and almost immediately got the codes P300, P301 and P304. I changed the spark plugs- I do not think they had ever been changed and reading this forum I saw that old spark plugs are a common cause of these misfire codes.
When I changed them, there was not any oil or liquid in the tubes. They came out and new plugs went in without incident. I reused the coil packs and started the car up. Same problem, tried resetting codes with a bluetooth odb2 adapter and the Car Scanner Pro app. Not sure things were actually cleared and I now I need to buy a dedicated scanner, but this was my best option.
Drove it a few times after, seemed like the same rough idle was happening and ran scanner again, cleared codes again, drove a few more times.
My question is will these codes go away if the problem was caused and solved by the spark plugs automatically?
And if so, how many drive cycles do I need?
The last time I had a code it was related to the thermostat- I replaced it and the codes were still there, and after driving for a while they simply went away, but in this situation I am worried that if the cylinders are shut down they will not come back on to clear the codes...
Thank you for any responses and information.
I changed my oil and engine air filter at about 140,000 miles on a daily 2010 ML350. Trying to be as economical as possible here, after doing the changes drove and almost immediately got the codes P300, P301 and P304. I changed the spark plugs- I do not think they had ever been changed and reading this forum I saw that old spark plugs are a common cause of these misfire codes.
When I changed them, there was not any oil or liquid in the tubes. They came out and new plugs went in without incident. I reused the coil packs and started the car up. Same problem, tried resetting codes with a bluetooth odb2 adapter and the Car Scanner Pro app. Not sure things were actually cleared and I now I need to buy a dedicated scanner, but this was my best option.
Drove it a few times after, seemed like the same rough idle was happening and ran scanner again, cleared codes again, drove a few more times.
My question is will these codes go away if the problem was caused and solved by the spark plugs automatically?
And if so, how many drive cycles do I need?
The last time I had a code it was related to the thermostat- I replaced it and the codes were still there, and after driving for a while they simply went away, but in this situation I am worried that if the cylinders are shut down they will not come back on to clear the codes...
Thank you for any responses and information.
Joined: Nov 2016
Posts: 7,847
Likes: 3,497
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
No, they will not go away on their own. You have misfires in cylinders 1 and 4, which are the two in the front of the engine. Recheck spark plug torque and connections. If the plugs are new, try moving one of the coil packs to another cylinder and see if the problem moves or not.
Thread Starter
Junior Member
Joined: Mar 2013
Posts: 15
Likes: 0
2010 ML350 W164
OK I swapped the coil on cylinder 1 with the one on cylinder 2 and I am still getting the same P301 and P304 and P 300 error codes.
any additional thoughts? Again, it was right after an oil change and an engine air filter change. Swapped out all the spark plugs in response to those error codes, and here I am.
any additional thoughts? Again, it was right after an oil change and an engine air filter change. Swapped out all the spark plugs in response to those error codes, and here I am.
Joined: Nov 2016
Posts: 7,847
Likes: 3,497
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
This is basically the procedure you followed, but the problem did not move.
So, the next thing to check would be the connectors and wiring harness foe the two cylinders. If they look good, then do a compression test on cylinders 1 and 4.
So, the next thing to check would be the connectors and wiring harness foe the two cylinders. If they look good, then do a compression test on cylinders 1 and 4.
Joined: Nov 2016
Posts: 7,847
Likes: 3,497
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
A little techy, but worth watching. Since you have specific cylinders identified, I doubt you have a fuel problem. But still worth checking.
Joined: Nov 2016
Posts: 7,847
Likes: 3,497
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
OK I swapped the coil on cylinder 1 with the one on cylinder 2 and I am still getting the same P301 and P304 and P 300 error codes.
any additional thoughts? Again, it was right after an oil change and an engine air filter change. Swapped out all the spark plugs in response to those error codes, and here I am.
any additional thoughts? Again, it was right after an oil change and an engine air filter change. Swapped out all the spark plugs in response to those error codes, and here I am.
