Check Engine Light / Exhaust Filter Message / K&N Filter

[craigth]

I have a 2008 2500HD Crew SWB 4WD. Recently I've been getting a check engine light at idle very quickly, less than 5 minutes. The message indicates it's the exhaust filter as part of the emissions and it goes temporarily into reduced power until you drive it for a minute or two.

So I took it into the dealer. They determined the problem was related to the K&N filter. If they removed the K&N filter or put back the stock filter which I still had with less than 500 miles on it there was no error code thrown.

The K&N has been in there for 13K miles with no issue and was really clean. The mechanic thinks it may be the MAF sensor located on the air intake tube but isn't sure. So I need to monitor the situation with the stock air filter.

Anyone have an ideas as to what is causing the error code? Anyone have a similar problem with K&N filters?

I run K&N in all my vehicles and never had a problem like this.

[DmaxMaverick]

If you do only/mostly town/city driving (lower speed, stop/go), the DPF (Diesel Particulate Filter, in the exhaust) hasn't had opportunity to regen (run the clean cycle). The truck needs to be driven at/near highway speeds and/or with a significant load for a given period to complete the cycle (or the computer won't be happy, and reduce your power/fuel, among other things). While the K&N filters can cause MAF issues from too much oil (contaminating the MAF sensor), it isn't likely causing your current problem. The dealer should have addressed the DPF regen issue before anything else. To blame the issue on an aftermarket filter, absent of supporting DTC's or symptoms, is irresponsible on their part (doesn't seem too uncommon, lately).

[Mark Rinker]

...many here have come to the conclusion that oiled gauze filtration is fine for gas engines, but not for turbo diesels due to the volume of air that they must filter, and the importance of keeping even the most minute amount of silica (sand) out of the engine.

Oiled gauze filters flow slightly better, because they let more particulates through.

The factory filter from '06 and newer is a great peice, IMO - tons of surface area, not prone to plugging, maintenance free, etc.

[agmakar]

I had the same problem last month. I took my truck to the dealer, they replaced my MAF. The check engine light came back on after two weeks. So I took my truck back to the shop, they then replaced the computer module and the Check engine light came on one week later. Finally I took my truck back to the dealer where they cleaned the MAF this time and the check engine light came on within hours.

We then knew it was the K&N filter causing the problem I replaced the filter with the factory filter and now there has been no problems since, also my Fuel Mileage jumped up a whole MPG. I'm getting 18 MPG combined HWY and city driving and I drive between 70 and 75 MPH here in Utah.

I have a 2006 Chevy 2500 HD with 30,500 miles, with Goodyear MTR's (30,500 miles as well with excellen tread remaining) stock size.

[DmaxMaverick]

The issues that come up with aftermarket filter elements and systems (not just K&N) are not solely related to the "type" of filter, or the filter element technology. Most of the issues, according to my experience and research, is more related to the airflow characteristics, rather than the actual airflow volume/restriction. These systems, be it stock or aftermarket, are not laminar flow. They are turbulent, and each has its own characteristics. Changing any component will effect how the air is read by the MAF. The stock system and MAF are designed to be happy together. The sensitivity of the MAF value parameters is very close-tolerant. It doesn't take much to get the PCM in an elevated state of defense, so to speak.

You have 2 options. Either do what's necessary to keep the MAF/PCM relationship healthy, or change the rules with aftermarket programming to broaden the tolerance. Aftermarket companies do a fair job of R&D, but they can't account for every detail, as even identical vehicles will have unique variations. Unique calibrations can (and are, in many cases) be made at the mfg level. However, throwing an aftermarket wrench into the works reduces this ability and the Mfg's willingness to accommodate unique conditions.

As you've found, the dealer has but one option, initially: suggest you restore your vehicle to original condition before attempting diagnostics/repair. Some dealers are more forgiving with this than others, but may not be doing themselves or the consumer a service with this practice. If it checks out, it is up to the consumer to accommodate issues with non OEM components.

[Runaway_Dmax]

Oiled filters from what I have seen or heard do one of two things. Coat the Maf sensor with oil giving off an error message or flows too much air and sensor detects it and an error message. If you are getting the message "clean the exhaust filter," someone already mentioned to drive above 30 mph for about 17 - 20 miles and it will regenerate the DPF (exhaust filter).