Range Extender won't start - Inlet camshaft sensor error

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codepoet80

New member
Joined
Sep 19, 2021
Messages
4
Hi all, new here and new to a 2015 i3 Rex.
Bought the car off a generic used dealer for a great price a couple weeks ago. Replaced the 12V battery with a brand new one from Remy, after trickle charging it fully. Coded the car for HSOC but resolved not to run the Rex until I could do an oil change. Finally got everything done this week, and fired it up in Emissions Test mode. The Rex started up then immediately shut down with a Drive Train malfunction error.
Read through all the forums and replaced the fuel pump relay. No change.
Read the codes, they said misfire on cylinders 1 and 2 and camshaft sensor error.
Spoke to the dealer, he said, maybe it was sitting with old gas too long. So I tricked it into running in HSOC by clearing codes a few times while it was on, then drove it around late in the night until the tank was empty. It ran brilliantly once I got it started: smooth with no codes, and was a real treat for battery life!

Today I put a tank of fresh gas in it, and fire it up again. Same errors, same symptoms. Tricked it into running in emissions test mode by clearing codes, and let it run to flush anything in the lines. Took it for a drive. Same errors, same symptoms.

At this point, I'm pretty sure I have a problem, but not sure if its just a bad sensor or its an actual camshaft problem. Does anyone have any experience or advice they can share?

Exact code is: 104004 "Inlet camshaft sensor, electrical: synchronization error"
The engine training manual, page 8, suggests this sensor is pretty close to being user accessible. Has anyone replaced it?
https://attachments.priuschat.com/attachment-files/2016/07/108943_12_W20-Engine.pdf
 
Sorry for the frustration. This is why I'd take my car to the dealer to have this battery replaced. It just isn't worth the headache and frustration changing out this battery causes as a DIY.
 
Does the dealer you bought from have a 30~90 day warranty?

It is possible that the previous owner had this failure/error, cleared the codes and traded the car in rather than fix it. Inexpensive part but can be an expensive repair. One similar I saw on a post, to do the repair, the BMW Dealer had to drop the engine out of the car (was still under warranty). Out of warranty, the labor charge is likely going to be pretty high.

If no recourse from the used car dealer, might be worth paying the $200/$300 diagnostic charge at a BMW Dealer for an exact determination (and cost estimate).

Also, check the oil level - one possible cause of cam sensor failure is excessive heat/low oil.
 
No warranty from dealer (knew that going in). Oil levels are pristine.

Why should they have to drop the engine out of the car? I can see the sensor, and the screw that holds it in, not 3 inches from the oil dipstick. Its a little buried by the engine cover, but it's right there...

download.php
 
Just what another i3 owner posted with somewhat similar issues - said they ended up replacing the camshaft position sensor.

https://www.mybmwi3.com/forum/viewtopic.php?t=3016
 
Thanks for posting the related issue. I think that person got taken for a ride. The sensor is a $50 part, and getting to it is no harder than replacing the sparkplugs:
https://www.youtube.com/watch?v=XHnQmPLXuj0

I'm going to enlist the help of a mechanic buddy and try this myself (with his guidance!) I'll report back here whenever I get around to doing it. You can see the sensor just beside the sparkies in that video -- its held in by a single bolt.
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But is that sensor bad? Or just indicating that there is a sync error with other sensors? In all the posts - no search comes up with a bad inlet camshaft sensor, or someone having to replace an inlet camshaft sensor due to REx failure. Several postings of having to have the camshaft sensor replaced, after similar symptoms. Someone posted just a few minutes ago on the World Wide i3 FB group, that he has been driving around for three years with an inoperable REx, because the Dealer wants 3K+ to replace the camshaft sensor, with similar symptoms.

Guess you could replace the sensor and see.
 
That's the right question, for sure. For $50 and an hour of shop time, it seems like it would be worthwhile to find out.
As noted, the engine actually runs fine -- if you trick it into running by clearing the codes.
 
Yup. But expect more than $50 an hour though. Most BMW shop labor is $150 hr. minimum. I think when I took mine in for the fuel pressure sensor, was told that diagnosis alone would be $230 - and waved if that actually turned out to be the problem, as the FPS has an extended 10 yr warranty because of a high failure rate - which mine was, so the extended warranty covered it. If it had turned out to be something else, I'd have had to pay the $220, plus whatever the repair cost. (The fuel pressure sensor unlocks the fuel door when the tank depressurizes for filling - faulty ones don't recognize when the tank has finished depressurizing, so won't unlock the fuel filler door).
 
codepoet80 said:
That's the right question, for sure. For $50 and an hour of shop time, it seems like it would be worthwhile to find out.
As noted, the engine actually runs fine -- if you trick it into running by clearing the codes.

Just wondering if you were able to get the sensor changed and if it resolved your problem?
 
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