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Engine stalls on hwy/ in intersection, temperature sending unit?

1608 Views 23 Replies 5 Participants Last post by  Brandon Lanning
Hello out there,
I have a 2004 beetle, 2 litter, Manuel, with 100K miles. Just drove across Midwest with no problems but near the end of trip engine would stall on hwy. Not really die, just absolute loss of power then jolt back to life in 3 to 5 seconds. Now it does it when I'm taking off in intersections also. Only twice has it really died and it started back up easy. No lights have come on in dash. And I know lights work because they all come on as normal when I turn the ignition on. Only thing that seems consistent it it only happens on hot days or after driving high speeds for hours. But still no temp lights!
I just read post on this forum on engine speed senser by red99 posted may 12, 2013. This looks like my problem but before I start replacing things can anybody tell me if without check engine light coming on could it be a temp. sending unit? Is there more then one temp. sending unit in question?What about MAF senser? Does MAF senser ALWAYS trip codes as I've read? Can I have tripped codes without engine check light on? Someone said that somewhere!
Any help appreciated. Thanks. Brandon
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As always, FIRST step; scan for trouble codes any codes, can be in memory without check engine light being on. Most, issues like you are describing; end up being fuel delievery or ignition related problems or component failures.

A number of possibilities, come to mind (failing fuel pump, coil pack, crank, maf sensor, dirty throttle body, etc; just to name a few); most auto parts stores will scan for trouble codes, for free.

Post any trouble codes you find and we can go from there.
The cars ECU can contain what are called "pending" codes. These codes haven't been in the ECU long enough to trip the check engine light, but a good code reader will be able to pick those up.
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Both helpful. I was unclear on the pending codes issue.
Before I had a reader, I had a similar issue with daughters and no CEL either. Was the speed sensor you mentioned. I got lucky. Be sure to look at VCDS before you go shopping for a reader.
near the end of trip engine would stall on hwy. Not really die, just absolute loss of power then jolt back to life in 3 to 5 seconds.
Does the tach go to 0 even though the engine is still turning when this happens on the highway? If so, it is the engine speed sensor.
Any updates; find any codes?


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As far as codes, No. I took it to O'Reilly. They assured me they could pick up on any codes, even if only "pending".
To answer red99, I can't tell because if I push the clutch in when running high rpm by the time the rpm drops low enough to to idle it has already come back to life.
But in intersection when it has done it did drop below idle. Then it ran really low and rough for about 3 seconds. Once it died, but I think I was partly on the clutch that time.
Of course I haven't paid that kind of attention to those details more than twice because I usually have traffic coming at me or people honking behind me.😬😭
I did order speed senser yesterday so will try that. Sounds like it is the problem.
A bad crank/engine speed sensor; will typically, throw a trouble code like this.


And/or this:



For a replacement sensor; stick with oem Bosch, avoid failure prone aftermarket parts.


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If the sensor replacement doesn't fix it; i would be looking at fuel delievery issues.

A dirty throttle body; can cause stalling problems, a clean, possibly a nee hasket and throttle body alignment, would be a fix for that.


I have had similar symptoms to what you are experiencing with a dying fuel pump. Like many electrical components; the fuel pump was initially., working fine when cold, when the engine was up to operating temps and hot, then it would start malfunctioning. The symptoms were progressively getting, worse over time; at highway speeds, or under load, the engine would cut out. Also, if the started the car cold, it would be fine and then, after driving awhile, parking at a store; then, heat soaking, (temps rise; when turning off the car). After coming back from the store visit; it would be hard or would't start (after a cool off period; it would start again).

Failing fuel pumps themselves; typically, don't throw trouble codes but there was a lean code. Fuel pressure testing, showed normal psi @idle but under load the pump; could not maintain needed volume. Sometimes, you will also see; the check valve is stuck open and it cannot maintain residual pressure, goes immediately to zero, when the engine is turned off (this hard start issue/symptom, is more consistent; not brought on by heat related factors).

For replacement fuel pumps; stick with only oem VDO or Bosch, cheap aftermarket pumps, are notorious for failure or defective out of the box. Airtex and O'Reilly's Import Direct brand pumps; have been documented as very poor quality by members on this site. We have a ton of diagnostic discussions; where a cheaper aftermarket pump is installed, doesn't work right and the final reliable fix, was a replacement oem Bosch or VDO pump.


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If you give us the 2.0L engine code, (sedan or convertible?); we can give you some service manual links for testing and repair info.
If you give us the 2.0L engine code, (sedan or convertible?); we can give you some service manual links for testing and repair info.

Well, I'm back. Got very busy with work and let everything sit for a while. Actually we have been driving beetle quite a bit and I thought I had fixed it, as I did replace cam position sensor shortly after last post. Last weekend it suddenly stalled again and did several times. I bought quality cam position sensor from O'Reillys.
Engine is 2.0L, 115 HP, B1B-051C, hatchback, NOT convertible. If someone out there can still suggest service manual links I would appreciate it.

Thanks 👍
Have you scanned for codes yet?

Unless the cam sensor was an oem in an off brand box which is unlikely coming from a parts store (O’Reilly’s) you will have actually bought the best chinese sensor O’Reilly’s sells. Which is why we suggest using quality parts from the dealer either a local dealer or an on line dealer who sells oem parts. Chinese parts are generally junk and last only a short time (2 months?) which wastes your money and time. If O’Reilly’s gave you a lifetime warranty with that part go get it replaced for free and if the problem is again solved order an oem one to have on hand when the new one fails.
Last weekend it suddenly stalled again and did several times. I bought quality cam position sensor from O'Reillys.
The stalling problem is caused by the engine speed sensor (aka crankshaft position sensor), not the cam position sensor. They are not the same thing. When I asked whether the tachometer dropped to 0, if the engine speed sensor stops working and has caused the sudden loss of power, the tachometer will read 0 even though the engine is still turning lots of rpms, like if the car is running at highway speeds and the clutch is still out.
Definitely, get the car scanned for trouble codes; did you ever clean the throttle body?

As noted, the crank position sensor; has been a sensor, that can cause a hard start or dying problem but typically throws a trouble code.

Any sensors that need replaced; stick with oem Bosch brand sensors, the same from the VW dealer. I would avoid O’Reilly’s as they typically sell their “import direct” house brand of parts and they are known, to be low quality. AutoZone has Bosch sensors; sometimes, sold through their Duralast brand, check in the box before purchasing, to make sure or they can normally special order under the Bosch brand or use a online supplier like fcpeuro.

If you do not have your own scan tool; you might consider something like a OBD II elm 327 wireless dongle and a app like OBD fusion or dash command, running on your phone. VW specific scan tools; consider VCDS by Ross tech or OBDEleven.

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Based upon your original description of temporary loss of power at highway speeds and load, a failing fuel pump, could be a possibility. Quality oem fuel pumps; are available from VDO and Bosch with the latter, being more cost effective.


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Fuel pressure specs and testing:



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Have you scanned for codes yet?

Unless the cam sensor was an oem in an off brand box which is unlikely coming from a parts store (O’Reilly’s) you will have actually bought the best chinese sensor O’Reilly’s sells. Which is why we suggest using quality parts from the dealer either a local dealer or an on line dealer who sells oem parts. Chinese parts are generally junk and last only a short time (2 months?) which wastes your money and time. If O’Reilly’s gave you a lifetime warranty with that part go get it replaced for free and if the problem is again solved order an oem one to have on hand when the new one fails.
👍 Will do. Do you have a recommendation on testing the cam sensor? I kept the old one I took out and would like to confirm that bad cam sensors is what I'm fighting.
And yes, I have tested for codes twice. Both times nothing pending.
Did you do any fuel pressure testing?

Here is a video; about cam sensor testing.

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