# 30FF code updated to a 30FC code after new Spark Plugs



## Managementpub (Aug 3, 2018)

30FF code updated to a 30FC code after new Spark Plugs

Originally, once i accelerate hard for a couple of seconds, gaining fast incremental speed, the engine light will come on and suggest that there's an engine malfunction AND that it will operate at reduced power...initially I really didn't see any measure of reduced power accelerating or steady driving - and if so, not even close to the power reduction I experienced position sensor went faulty.

Just testing it a couple of months later I have seen a gradual power lag when in limp mode and I will top off at 70mph regardless if I'm still trying to accelerate in standard or manual shift...rpms Increase but not speed after 70mph.

I can clear the engine warning light and malfunction message by restarting the vehicle and it won't reappear until I do a hard and steady acceleration again which I normally don't - really only to test.

When I initially ran a diag I got code 30FF after the hard accelerations. I put in new spark plugs a couple days ago (coupled months later bc the car was misfiring/hesitating and cut off while idling a couple times over a series of days - which never happen before), did a hard acceleration to retest and still got the engine light and the engine malfunction warning. Ran the codes and got the 30FC code this time.

I see members have resolved the same problem using different methods (spark plugs, coils, hose leak, pipe, etc.) and people have advised different ways to start troubleshooting.

I am providing an update since I received a slightly different code after changing the spark plugs. Because the plugs were pretty old, I think I will replace the coils as well to start, then test for leaks.

*****Here are some initial suggestions I received after getting the 30FF code but before changing the Spark plugs.

1.) If you still have your stock plastic charge pipe, I'd take it off and look for cracks. It's a known weak point on the 335's. Loose clamps and bad O-rings to the throttle body are another thing to look for.

Also if your diverter valves are sticking, you'll get low boost. You can pull off the hoses leading back to the turbo's cold side and listen for blow off.

Being 10 years old, the charge pipe would be the 1st place I'd look.

2.) Anybody who suggests coils or plugs as a fix for 30FF has no clue what they're talking about. 1. Test the boost control hoses 2. Test for boost leaks 3. Only then consider a problem with the turbochargers

This guy kinda does things the hard way, but he directs you very well to all the hot spots. http://www.n54tech.com/forums/showthread.php?t=13114

To test the boost control hoses, just get a MityVac, disconnect a hose from the top of a vacuum canister, and see if the system will hold vacuum. Most common cause of this error is the two little boost control hoses that go across the head.

They disintegrate behind the oil filter housing. For both, it's like $50 for OEM or $5-10 for AutoZone.
When do you get smoke?

3.) Over 60k mi, especially if power mod? Better check that charge pipe - may have connected OK but under press, cracked. Every charge pipe will break eventually, the BMW way.

First things first: Check the charge pipe connection, no more than removing the air box & taking a peek. Air box pulls right off rubber grommets but there is a sensor or two to disconnect....Google....

Any further input would be a good help.

Thanks,

2008 335i


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## marcozandrini (Feb 13, 2014)

What scanner are you using? What do the codes mean?


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