Misfires happen from time to time, especially in cars that are in their teens. For most bimmer owners, diagnosing a misfire goes something like this. After starting the car and noticing that something’s not right, you go ahead and check the spark plugs. If the spark plugs are good, you check the ignition coils by moving them around.
If those are good, you check to see if the misfiring cylinder is getting fuel. In a scenario where all these things are fine, and you’re still dealing with a misfire, there’s either an issue with compression or something completely different is at play. OBD-II codes usually help reveal what’s going on. When faced with this type of situation, many BMW owners find themselves staring at a 2A82 intake VANOS code and not much else. What does a VANOS code have to do with engine misfire? Let’s find out!
2A82 Intake VANOS Code — Meaning
VANOS was introduced in the ‘90s as BMW’s answer to the variable valve timing craze that was going on at the time. Every manufacturer came up with a design of their own, but most of them either used cam phasing VVT, like BMW, or cam changing VVT, like Honda. We’ve already discussed VANOS in detail, so we won’t go into it here. The important bit for our topic today isn’t how the VANOS system works, but how it’s actuated.
The gears that phase cam timing are driven by oil pressure. Since it wouldn’t be feasible to have oil running through the VANOS system at all times, there are two solenoids (or one, depending on the type of VANOS setup you have) that open and close when the DME decides to adjust the cam timing — one on the intake and one on the exhaust side.
When you scan for codes and find a 2A82 error (a BMW-specific code, mind you), that means that the solenoid on the intake side is malfunctioning.
Misdiagnosing the Issue
Although OBD-II codes make life easier, they are not the be-all, end-all solution to diagnosing car issues. The reason is that there is usually more than one thing that can trigger a code. Sometimes you’ll find several codes logged by the DME, which is usually enough to point you in the right direction. However, with codes such as 2A82, things are a bit trickier.
After reading this code on the scan tool, most people would simply remove the intake VANOS solenoid (since it’s easily accessible), replace it or clean it, and call it a day. This approach works if you have a bad solenoid. However, as we’ve mentioned earlier, there is more than one cause for the 2A82 code. In this case, that other cause is none other than your oil filter housing cap. What does an oil filter housing cap have to do with variable valve timing? On paper, nothing.
However, most things in your engine are connected one way or another, which can sometimes cause odd issues like the one we’re about to discuss.
Before we get there, let’s make sure that it’s not actually the VANOS solenoid that’s gone bad. The easiest way to test this is to take your intake and exhaust solenoids and swap their places. If the code goes from 2A82 to 2A87, chances are that you have a bad solenoid. It’s worth mentioning that these solenoids have a lifespan of around 50,000-70,000 miles, depending on how well the car was maintained.
In some instances, the solenoid itself might be perfectly fine, only dirty. Missed oil changes sometimes lead to the formation of oil sludge, which is enough to clog up the tiny strainers on a VANOS solenoid.
Lastly, you can bench test the solenoid by feeding it battery power. It should open when you hit it with 12V.
The Phantom VANOS Intake Solenoid Problem
Where things go awry is when replacing the solenoid doesn’t fix the code or the misfire. At this point, many owners begin to dig deeper into the VANOS system. While that is sometimes necessary, you can save yourself quite a bit of money and time by simply taking a look at your oil filter.
As it turns out, the oil filter housing on most I6 engines of the E90 era, like the N52 and others, relies on the oil filter housing cap to form a seal between the filter and the oil bypass bore that sits in the middle of the housing.
The oil filter cap features a plastic cage that has a small O-ring at the bottom. When you replace the filter and put the cap back on, this cage goes through the middle of the filter. More importantly, the O-ring at the bottom of the cage forms a seal on the bypass bore when you crew the cap on tightly.
What often happens is that the cage separates from the oil filter cap. Much like other parts of your bimmer’s engine, the cage and the cap are made of plastic. With time, due to exposure to endless temperature cycles, this plastic becomes brittle.
Once the cage breaks off, there’s no guarantee that it will properly seal off the oil bypass bore. When that happens, oil is directed down into the oil pan instead of the engine, which reduces the oil pressure.
Guess what needs oil pressure in order to work? That’s right — your VANOS solenoids.
Before you go and pull the trigger on hundreds of dollars worth of VANOS parts, it’s a good idea to take a peek inside your oil filter housing.
How to Prevent Oil Filter Cap Issues In the Future?
There isn’t much you can do about this aside from getting a new oil filter housing cap when the old one breaks. There are aluminum aftermarket caps out there, but they are often not profiled the right way, causing them to seep oil and leak.
In any case, you will have to replace the cap with the cage. That is the only way to prevent oil pressure issues in your engine stemming from the faulty oil bypass seal.
If you’re looking for Genuine BMW oil filter housing caps, you can find them in our catalog. Head over to our store section, select your car using our car selection tool, and search for the parts that you need! It’s that simple.
