Year: 2008
Miles: 159,298
Codes: P0420 (10+ years), P0017

Hoping to find someone with a more experienced ear than mine to help identify an increasingly noisy whine during acceleration, especially when the car is first started and throughout the entire engine warmup period. I've linked my video below where I tried to capture the whine while driving as well as when parked and I rev the engine a bit. There have been several seemingly related issues leading up to this noise coming from underneath the car which I'll detail below, but the whining has come on steadily over the past several months I'd say. It eventually gets drowned out by the engine when getting up to speed and seems to almost disappear completely after I've driven around for ~30 minutes. Other than feeling a more pronounced slip when driving slow and then getting on the gas right away, I don't really notice any drivability issues or much difference in the way it handles today. This car has been my daily driver for over 16 years now and I am very aware of any feelings or noises that I haven't recognized before. I feel like it's either the timing chain and components going bad or it's the torque converter but looking for assistance and recommendations for next steps based on what I've detailed here.

Issue Details
I wrote a lot on my first transmission problems back in September 2025 in my post P0741 Transmission Woes. I ultimately swapped out all transmission solenoids including the harness with OEM replacements and refilled the transmission fluid at 153,000 miles. Cleared the P0741 and it seemed to drive fine after that. Some time in October 2025, I noticed the engine sounded a bit different when driving. I'd say it was a bit of a deeper, rougher sounding growl than usual so I checked the codes and saw a P0017. I've basically had a P0420 code that's haunted me for the majority of 10+ years, so I don't know exactly when that P0017 code first showed up. I checked the wiring around the camshaft position sensor and cleaned everything up but the code came back on me. I have not swapped out either camshaft or crankshaft position sensors since getting the code.

The second noticeable change came shortly after the P0017. While cruising around 40-45 mph, I could start to feel the RPMs start to drop out of nowhere (no deviation in the accelerator by me). My dad drove a sweet 2001 BMW Dinan 540i back in the day and my engine sound reminded me of when he would take off from a stoplight in second gear instead of first. Not necessarily like it was going to die, but my H3 sounds and feels almost like it needs to shift gears or something. If I held everything in the same position, I sometimes get a loud vibration from the engine. As soon as I put a bit of pressure on the accelerator, everything goes back to normal.

A few months ago was when I started hearing a high-pitched whine when I pushed the accelerator. It was pretty faint at first but has steadily gotten louder and more pronounced. I have a magnaflow exhaust on it and used to love driving at low speeds listening to the deep exhaust growl. Now I hate it and feel embarrassed if people are around because of this high-pitched whine, lol. Again, no drivability concerns at the moment, just an annoying whine as I get going every day. I still feel the vibration if I hold the pedal steady in this exact spot around 40-45mph.

Any way to tell without taking it to someone to have them check? Other than a couple alignments, I haven't taken it in to a shop in 6 years for any kind of service, so that wasn't my first inclination here. Did some research and sounded like the torque converter could be a viable culprit. Can't be sure but it feels like the transmission is holding on by a thread! I don't have any plans to get rid of the car and I don't think I'll ever be ready to call it quits on her! As always, appreciate any help or suggestions and don't roast me too hard.

 

fan clutch, belt or a belt driven accessory?

 

I had my stethoscope out earlier and all seemed relatively quiet except for the backside of the oil pan right by that rubber piece covering the torque converter bolt location.

I’ve really got two issues that in my opinion are related: the whining sound when increasing the RPM slightly and the chugging/surging that happens at highway speeds when the engine is cold. I live and work in the same town and might only get out on the highway once every week or every two weeks so I just don’t experience that problem as often. The whine is steady no matter what and seems like it’s getting louder.

No metal-on-metal grinding noises or anything like that as of yet. Also virtually no metallic flakes or shavings found in my last oil change or on the VVT screens when I last checked a few hundred miles back.

 

Belt Pulley Bearing or Alternator Issues

• The Sound: A high-pitched, loud whine or whir that perfectly matches the revving of your engine.
• The Cause: A worn-out serpentine belt, or bad bearings inside the alternator or power steering pump. The faster the engine spins, the faster the pulley rotates, causing the whining noise.

Low Power Steering Fluid

• The Sound: A distinct, loud groaning or whining noise that is especially loud when you accelerate and turn at the same time.
• The Cause: If your vehicle uses hydraulic power steering, low fluid or a failing power steering pump creates a loud "airplane-like" whine. [1, 2]

 

torque converter whine?

 

Decided to eat the $80 and take it to Certified Transmission near me. Got a call back just now and they basically said it doesn't appear to be anything transmission-related. Plenty of fluid but looked to be in need of changing. Seems a bit early to go bad, though. I last drained at 153,000 miles when I changed the solenoids and harness. Maybe just didn't get enough "flushed out" with the last drain.

They also noted that I was two quarts low on oil. I'm at 159,539 miles right now and I last changed the oil in February at 156,440 miles. Don't remember when I last checked the dipstick but I didn't expect to lose 2 quarts in 3 months. Standard Mobil 1 High Mileage Full Synthetic 5W-30. No signs of leaking around the oil pan seal, drain plug, or the oil pressure sensor over by the secondary air pump. The transmission shop also noticed a leak around the front differential. I saw that last week, replaced the drain plug, cleaned up the bellhousing, and filled it back up but it might the front cover gasket. They were going to check the pinion seal area tomorrow morning to be sure.

Seems to be pointing towards the timing chain/tensioner/cam phasers going bad. Right before taking it to the shop, I started it up and took the oil fill cap off to listen for the source of the whining noise that keeps getting louder and I could hear some clunking and faint metallic grinding as it idled. I don't know how else to confirm other than ripping it apart to get the cover open. The transmission shop basically recommended going to a general repair shop. The oil loss is concerning.

 

If it was 2 qts low on engine oil, I'm sure you heard noises with the oil cap off!

I know my engine will consume oil a lot faster if I'm on the interstate. Make sure both oil vents at the rear of the valve cover are clear. Might want to run some Liqui Moly LM2020.

 

Did you check with the serpentine belt removed?
Simply remove the serpentine belt===> drive without power steering assist & alternator recharge>>>>>>>make sure to monitor engine temperature on the gauge!
WITH BELT REMOVED IS THE NOISE GONE?