05 Beetle 1.9L GLS TDI - P0101 & P0128 Error Codes

Hello! I recently just purchased a 2005 VW New Beetle GLS TDI that the local non-VW repair shop could not fix. It has a new long block engine put in about 50,XXX miles ago. The issue is it keeps tripping P0101 and P0128 error codes. They did try cleaning the MAF sensor, installed new fuel filter, installed new cam position sensor. I have read on here a few others were having this issue even after changing out the MAF sensor. Their remedy was to install a new camshaft. Is this a plausible solution?! Could the coolant temperature sensor also be an issue?

There is a few issues with the Bug right now. One is that it is hard to start. The first start after setting overnight it fires right up, but after that it takes a lot of cranking until it fires. I have noticed when I first turn the key on there is a sound like rush of fuel from lift pump to tandem pump. I have read there is issues with fuel pressure loss on tandem fuel pumps. Is this what the issue could be?

The other issue is at idle the tensioner pulley on the serpentine belt vibrates and it will quit vibrating if I rev the engine even slightly. Also at idle when you turn the steering wheel it will squeal the belt. Is this a bad/worn belt tensioner? The power steering pump has also been replaced recently.

Thank for the help!!

The belt is likely the alternator one way pulley locked up.

A new coolant temp sensor, OEM thermostat, neck, and o-rings will likely take care of the P0128.

P0101 is likely a very minor boost leak or a false air leak somewhere in the air inlet or charge air tract, and it sometimes helps to use a smoke machine to find them if any oily residue is not evident yet anywhere (on the charge side).

The long crank when hot can be fixed with software.

oilhammer said:

P0101 is likely a very minor boost leak or a false air leak somewhere in the air inlet or charge air tract, and it sometimes helps to use a smoke machine to find them if any oily residue is not evident yet anywhere (on the charge side).

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The hose from intercooler to turbo is loose and also found one of the ears slightly worn, so will check that hose for a leak.

Thanks for the reply!!

I would have one of our tuners do this, and I would also go ahead and put a new set of the 7v NGK glow plugs in it while you are at it (the newest, and likely the last, revision) and tell the tuner this so they know how to set the preglow strategy.

My TDIs are tuned by Rocketchip, but there are others.

A dealer will not have a clue about any of this.

Is a long crank a common problem on the BEW? If not, could it be a fueling issue, perhaps because injectors were swapped over then the new block was installed, and not set up properly? Seems that some folks have lingering problems with properly setting injector torsion values on these cars.

Hot restart long crank times are VERY common on the BEW, yes. Oddly enough, similar to the 1998-1999 ALH. Those, too, can be fixed with software.

Just the BEWs. The BHWs and BRMs never have this problem. The BHWs in fact generally start so fast they are running as soon as the very first power stroke on one of the cylinders happens. Makes no sense that the BEWs are so different in that they share all the same CKP, CMP, and other sensors. The BRM is the one with different sensors.

Didn't know that. Weird. All my TDIs start really fast. My wagon fires on the first compression stroke, which I thought was a quirk of the engine. But it's now done it with two different engines. Probably why, at 356K, I still have the original starter in the car.

My 1Z, AHU, all my ALHs, and my BHW all start very quickly too. Although my Beetle's starter is getting pretty weak due to the fact that the PO drove around with a leaking injection pump for over a year, and it took lots of cranking to get it started.

TDI Tuner

oilhammer said:

I would have one of our tuners do this, and I would also go ahead and put a new set of the 7v NGK glow plugs in it while you are at it (the newest, and likely the last, revision) and tell the tuner this so they know how to set the preglow strategy.
My TDIs are tuned by Rocketchip, but there are others.
A dealer will not have a clue about any of this.

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Where are one of you tuners? Don't think this could be a tandem fuel pump issue?

Thanks!

I usually send my ECUs to Rocketchip, but there are others.

A tune will only address the cold start and match the software to the proper glow plugs.
I suggest you clear up other issues before you tune.
Malone and Rocketchip are 2 popular chip tuners. Rocketchip can be a bit harder to contact (call), but he will not ignore you.
http://forums.tdiclub.com/member.php?u=8855
http://forums.tdiclub.com/member.php?u=16803
Both have websites, for your needs you'll want to call.

BobnOH said:

A tune will only address the cold start and match the software to the proper glow plugs.
I suggest you clear up other issues before you tune.
Malone and Rocketchip are 2 popular chip tuners. Rocketchip can be a bit harder to contact (call), but he will not ignore you.
http://forums.tdiclub.com/member.php?u=8855
http://forums.tdiclub.com/member.php?u=16803
Both have websites, for your needs you'll want to call.

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That is not true. See my above post, #7.

Here is a post by someone who knows more of the ins and outs of the software problem the early BEWs had:

http://forums.tdiclub.com/showpost.php?p=5222267&postcount=10

oilhammer said:

That is not true. See my above post, #7.

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If you say so, then it's not true.
I didn't know a tune would fix a bad temp sensor, bouncing pulley, tandem pump or in tank pump.
As always, your diagnosis is right on, I meant to suggest he clear up the dumb stuff first.

There is also TDTuning.com (sales@TDTuning.com) Mike has been tuning TDI's for a long time, and has a very solid reputation as well.

It cannot fix broken mechanicals, but the "long crank after hot soak" problem is pretty well known to be fixable with software on the BEW. The early ALH had a similar problem, that can also be fixed with software.

I've fixed more of these than a lot of people will ever see. Again, the folks that actually get into the software, code, hexidecimal, whatever you want to call it, know more precisely what is happening and why it happens. And when I get a BEW ECU back from getting a new reflash, they fire right up hot or cold just the same.

There is also an issue with a poor ground on the ECU, as well as another CMP issue (TSBs for those, too), but that manifests itself differently, and is often accompanied with a DTC.

But, as many of us know all too well, the BEWs also had the silly glow plug fiasco, so when tuning the preglow "palpitation" values must also be set properly based on which voltage glow plugs (5v or 7v) are being used. You use the wrong version, you get hard COLD starts, or very short glow plug life.

So when getting a BEW tuned, these are all things that should be addressed for the best running engine. And this is an aside from any power adding software you may or may not be after.

oilhammer said:

A new coolant temp sensor, OEM thermostat, neck, and o-rings will likely take care of the P0128.
P0101 is likely a very minor boost leak or a false air leak somewhere in the air inlet or charge air tract, and it sometimes helps to use a smoke machine to find them if any oily residue is not evident yet anywhere (on the charge side).

Click to expand...

I am going to order the parts for the coolant sensor/tstat today. I plan on also ordering a jug of coolant. Anything else I should need?

I also and trying one new hose that just seems loose and now sealing to help with the P0101 code. I haven't tracked down a smoke machine yet, but will after the new hose is on.

Thanks again!

I don't know if you can get a "smoke pencil" where you live or not; the guys that do commercial air balancing use them all the time. The smoke generating compound is titanium tetra-chloride IIRC. It literally looks like a pencil and when you remove the cap the O2 in the air makes the TT generate the "smoke." I used to be a Balancing Engineer, that is how I know.

DrChris502 said:

I am going to order the parts for the coolant sensor/tstat today. I plan on also ordering a jug of coolant. Anything else I should need?
I also and trying one new hose that just seems loose and now sealing to help with the P0101 code. I haven't tracked down a smoke machine yet, but will after the new hose is on.
Thanks again!

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If you're changing the thermostat get the housing/coolant flange as well.

Thanks everyone...parts are on order and I am working on ordering a smoke pencil!

Well, good news. My beetle is FIXED!!! I got all the coolant parts on and added a FrostHeater to help keep the engine toasty while setting outside in the brisk South Dakota winters. That fixed my P0128 errors.

Now the P0101 error. After some researching and hooking to a computer found there was no signal from the cam position sensor. So checked the connection at the sensor and wiring. Found yellow wire cut and repaired that. Went to fire it up and give it a try, no start! Disconnect cam sensor and started after long crank. So this lead me to believe there may be a timing issue. So pulled timing belt covers off and found the timing was set incorrectly and camshaft was on tooth off. Reset the timing and plugged in all sensors, engine fired right up and runs great with no codes!

So the cam sensor not sending a reading to the computer was tripping the computer out thinking it was getting more/less air than it should with the current cam position and thus tripped a MAF sensor error code.

Thanks everyone for the help!!!

DrChris502 said:

......................So the cam sensor not sending a reading to the computer was tripping the computer out thinking it was getting more/less air than it should with the current cam position and thus tripped a MAF sensor error code.................!!!

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A great lesson in just how the car computer thinks, it's limitations and why there is no replacement for sound mechanics..
Nice work!

Thank you!

BobnOH said:

A great lesson in just how the car computer thinks, it's limitations and why there is no replacement for sound mechanics..
Nice work!

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Thank you! was not an easy find but did end up getting a resolution!