I Covered My BMW M3's Air Intakes With Bags While Washing It, Then Drove 20 Minutes With the Bags Still On, Now It's Stuck in Limp Mode and Smoking From the Exhaust

Few machines in the modern age have earned their stripes the way the G80 M3 has. Say what you will about the kidney grille that looks like it could inhale a golden retriever whole, under the surface, this car is the real deal. 

The twin-turbo inline-six is a torque-laden masterpiece, the chassis balance is sharp enough to leave scars on apexes, and the daily usability rivals some luxury sedans twice its price. 

Love it or hate it, the G80 is one of the most complete M cars BMW has ever produced. And for once, the internet seems to agree, the platform is nearly universally praised, from track rats to tuners to the guys who still name-drop the E36.

But even the best-laid engineering can't defend against human error, especially the kind born from good intentions. An anonymous G80 owner on the BMW G80/G82/G83 M3 & M4 Discussion/Marketplace Facebook group shared a post that’s since made the rounds:

“I was washing my car and covered the intakes with bags, then drove for 20 minutes with the intakes covered. The car is stuck in limp mode and smoking out the exhaust. Any ideas what I could have broken?”

How Covering A BMW G80 M3’s Air Intakes During a Wash Triggered Limp Mode

The answer, as it turns out, is quite a lot, but perhaps not permanently. 

Reactions poured in… Some brought clarity, others brought fire. Justin DiGiorgio gave a remote diagnosis: 

“You likely caused the breather crankcase to suck in excess oil from the negative pressure created from the restriction on the intake side... Clear the faults, and let the car idle for a while. If it’s good, go romp on it and blow all of the oil out of the pipes and turbos.”

But the online garage doors were just opening. Matt Duque chimed in with the grim reaper’s take:

 “It causes lean conditions, which is one of the most popular reasons for engine failure. If you say it’s blowing smoke, I’d bet you toasted the motor.” 

He then added a nugget of real-world advice, possibly immoral: 

“Take it to the dealer and say it randomly started acting up… definitely don’t mention putting the bags over them.” 

For context, the G80’s crankcase ventilation system isn’t some casual plumbing job; it’s a delicately tuned circuit designed to relieve pressure and keep oil vapor from cooking your intake valves. 

BMW G80 M3 Owner Reviews: Monster Acceleration, Daily Comfort & Unexpected Bulk

• Owners and forum reviewers praise it as a “monster” in straight‑line acceleration, noting it feels planted and powerful even with stock suspension
• Many appreciate its daily‑driver comfort, saying it’s “on a different level” for refinement compared to earlier M3 generations
• The car's size gets mixed feelings: while critics note it's bulky in person, they also say it “drives like a smaller car,” with agile handling
• Some in the community feel it’s "too insulated" and lacks raw excitement compared to earlier, more analog M3s, despite its capabilities

According to BimmerProfs and other independent BMW tech resources, obstructing the intake alters this balance, which can lead to the engine drawing in oil from the crankcase and coating the exhaust tract with it.

But not everyone was ready to hand out last rites. Manny Gonzalez offered another diagnosis: 

“Most likely oil in the exhaust system. You probably covered the oxygen sensors in oil and possibly any sensor in the bath of the air intake after the crankcase hose.”

His suggestion? 

A full sensor cleaning and perhaps a dose of Seafoam.

The G80 M3 is a marvel, no doubt. But like any high-strung athlete, it doesn’t respond well to being choked, literally. Covering the intakes may have felt like protecting your investment, but once the engine fired, those bags turned from defense to obstruction. 

The consequences? A confused ECU, sensors awash in oil, and the engine scrambling to breathe through any available passage, including its own crankcase. Issues that EV owners will never experience. 

But as with any good tale spun on the internet, especially one involving six-figure German machinery and a whiff of mechanical catastrophe, the plot thickens. 

Some commenters were quick to cast doubt on the story’s authenticity, noting that the image of the G80 used in the original post may have been “borrowed,” raising the specter that our anonymous poster might not be a misguided enthusiast after all, but a troll spinning wrenches in the comments section instead of under the hood. 

Whether this was a genuine misstep or a masterclass in digital baiting remains unclear, but the reactions, and the lessons, are real either way.

BMW G80 M3 Tech Specs: S58 Twin-Turbo Power, Performance Figures & Pricing Breakdown

• Powered by a 3.0 L twin‑turbo inline‑six S58 engine: standard RWD manual models produce ~480 hp and 406 lb‑ft, while Competition trims pump out ~510 hp and 479 lb‑ft with 8‑speed auto
• Performance numbers include a top speed of ~155 mph (electronically limited) and 0–60 mph in roughly 4.2 s (standard) to 3.9 s (Competition)
• Dimensions align it with the 5‑Series class, offering a spacious cabin and trunk (~480 L), though community comments note the large size is surprisingly nimble.
• base M3 starts around $69–76k, while M3 Competition trims (RWD or xDrive) begin near $ 86k, depending on options

The G80 will likely live to see another redline, especially if the owner follows the community’s advice. But the lesson endures: caring for performance machinery means knowing how it works, not just how it looks. Because sometimes, even with a car this good, less protection is more.

Image Sources: BMW Newsroom

Noah Washington is an automotive journalist based in Atlanta, Georgia. He enjoys covering the latest news in the automotive industry and conducting reviews on the latest cars. He has been in the automotive industry since 15 years old and has been featured in prominent automotive news sites. You can reach him on X and LinkedIn for tips and to follow his automotive coverage.