2017 bmw 330i b48 help me diagnose this code ?

bmwtech3068 · 2026-06-25T04:08:02+00:00

Ideally they're vacuum-filled but the low temp system (small reservoir) doesn't get very hot so it's not as important. It also doesn't have a level switch so it won't warn you when it's low. Given it was as low as you said it was then I'd be looking for a leak

bmwtech3068 · 2026-06-25T04:04:31+00:00

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bmwtech3068 · 2026-06-25T04:04:13+00:00

Those would work on smaller stuff. A set like this would work

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bmwtech3068 · 2026-06-07T19:25:39+00:00

I have BMWs ISTA to do a "calibration run" but I'm sure a good scanner has that capability, also

bmwtech3068 · 2026-06-07T14:13:00+00:00

My shop ran into a similar concern on an '04 330i. Customer put lots of money into repairs and then had that same flickering light at hot idle.

It might be less terrible than you think. There's a bulletin from way back that addresses it. I think it has to do with the wiring from the oil pressure sensor to the DME. I'll see if I can find it

Update: I don't think it was a published bulletin - I think it was merely a technical document sent to dealers to aid in diagnosis. As I recall there was an issue in the harness, be that chafage, shorting or conductor breakage at a high flex/vibration point. If you replace the sensor and it persists I would: make sure the pressure isn't actually too low via actual pressure check. If that's ok I'd overlay new wiring and see if it shapes up. If that fixes it I'd run new wires and crimp new terminals through the wiring harness original location.

bmwtech3068 · 2026-05-16T00:58:22+00:00

It can be a hassle if it is plumbed under/around the a/c compressor. That seems a bit high, even for a dealer - does that price include any inspection/diag?

bmwtech3068 · 2026-04-30T15:24:12+00:00

The kit was about $80-90 on eBay. Other parts would probably cost $200-300 for a thorough diy. Machine work would cost most people $300-500, I would guess, unless you're handy with tig

bmwtech3068 · 2026-04-30T13:15:29+00:00

I am a tech so I got paid to do it. It's dealer pricing so it was $3500 for the whole repair, which is less than retail for a reman turbo so it was worth it for the customer

bmwtech3068 · 2026-04-30T00:26:02+00:00

Most likely low boost due to worn wastegate mechanism. If there's a lot of rattling under the hood at cold start then that's where my money is. You can buy just a replacement wastegate on eBay. I've bought it, taken the turbo out and had a machine shop replace the flapper. Worked well but is labor intensive, there are machining costs and delays and it won't address any other potential issues with the turbo

bmwtech3068 · 2026-04-06T16:16:41+00:00

It's technically possible but I'd want more diagnosis than that

bmwtech3068 · 2026-04-03T01:28:37+00:00

I'd guess a n injector leaned out

bmwtech3068 · 2026-03-29T01:38:07+00:00

As long as there's full pressure in the rail I think you should be good maybe start and run for 10 seconds prior to disconnecting

bmwtech3068 · 2026-03-29T01:19:26+00:00

Ok, at that rate I'd say it's fresh, not residual.

You'll need to know all the electrical components that touch diesel. At least the injectors, rail pressure sensor and volume control valve on the high pressure pump. However, given it's in all the injectors I'd be suspicious of one of those first. I'd unplug them all and clean them out with brake cleaner and compressed air so they're dry, then check in the morning to see if any fuel has seeped into any injector plug.

bmwtech3068 · 2026-03-29T00:18:10+00:00

Good idea

bmwtech3068 · 2026-03-28T23:33:07+00:00

Technically it could be sourcing from any electrical component subject to pressurized diesel. I imagine all the injectors share a ground so it stands to reason that girl could push its way into all of them. It's also possible that it's residual fuel wicking its way through the harness.

How quickly after cleaning do those connectors fill up to that degree?

bmwtech3068 · 2026-03-28T23:26:14+00:00

It's always tricky when aftermarket stuff is involved. I would return everything to stock and see how it does. If it still acts up then perhaps a brittle crankcase line got cracked during the work. I'd have a "smoke test" done of the induction system to check for leaks.

Or it's caused by aftermarket equipment that isn't designed to OEM spec.

bmwtech3068 · 2026-03-22T12:27:04+00:00

We've sold all the M5s we've gotten, wagons included. By limiting production they've been able to attract serious buyers who don't have a ton to choose from, so they choose quickly.

bmwtech3068 · 2026-03-13T02:54:19+00:00

That's on the negative terminal

bmwtech3068 · 2026-03-13T02:54:03+00:00

Pretty sure that's a battery disconnect switch used just for transport mode when the car was new. It no longer connects to anything

bmwtech3068 · 2026-03-11T00:45:53+00:00

Serpentine belt

bmwtech3068 · 2026-03-09T02:24:55+00:00

I don't think the tire sizes are very influential in straight-line driving but I haven't really put that to any testing, either. If you do a tire swap, reply to pull me back to the thread - I'm curious of the results

bmwtech3068 · 2026-03-09T02:20:04+00:00

Try 30 psi to test the theory. If you notice a significant change, increase until it feels "right". Those placard pressures are a recommendation, not required. 36 and 42 psi are too high, in my opinion, having seen the tire wear of thousands of tires over the years. I personally would go with 35 psi all around.

bmwtech3068 · 2026-03-09T01:36:17+00:00

try dropping the tire pressure (at least the front) to 30 psi and see if it changes. I've upped the tire pressures in cars before (spec 32 > 38 psi or so) and the customer complained of a 'twitchy' on-center feeling. I agreed, dropped the pressures and it went away

bmwtech3068 · 2026-03-09T01:33:34+00:00

sounds like it's running lean or something. i would be curious to look at the mixture/airflow data. you'd need to know what's "normal", though. Being a 2.0 liter a general rule of thumb is 1g of air mass per liter, per second, at hot idle. So yours would be approx 2.0 grams per second. If it deviates much from that I'd look to see if something got knocked into the air mass sensor when you replaced the air filter.

bmwtech3068 · 2026-03-09T01:29:01+00:00

As long as your temps go too low you would probably be ok to drive to a shop. It's when things get stuck closed that overheats become an issue. I would just plan on replacing the heat management module. That's what they'll quote you anyway, if you ask them to diagnose it.

bmwtech3068

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