TheSamba.com :: View topic - Piggyback a cylinder head temp gauge from stock sensor?

Fri Nov 07, 2025 4:34 pm

I have recently been dealing with some lean mixture issues on my '79 bug. I knew something was not right because power was lacking in high demand situations and things seemed to be too hot at the back of the car despite no serious changes in oil temp. Spark plug check confirmed a lean mix and I am dealing with the clogged injectors. I would have liked to have known about the hot temps sooner instead of just "having a feeling" that the heads and exhaust were too hot. Has anyone tried to piggyback a cylinder head temp gauge to the stock sensor? That would seem like a cleaner install for a temp gauge...

Thanks for you input,

Hans

Fri Nov 07, 2025 4:50 pm

I have wondered about this... using the Type 3 heads on both sides means you could fit another temp sensor on the 1-2 side, leaving the 3-4 side sensor to work the FI.

Now the mapping of the sensor resistance to temperature used to be near impossible, but there are now programmable translators that let you mix and match sensors and gauges, usually for gas tank levels. I suppose one could make a setup like that for heat temp.

One caveat is how fast the sensor will react to hot heads. VW chose a location that reacted in a slower fashion than, say, a spark plug temp sensor.

But this might open up possibilities.

https://www.tanksinc.com/index.cfm/page/ptype=prod...de6p64fKtv

Fri Nov 07, 2025 5:01 pm

The TS2 isn't in a location that provides instant readings, it's just to determine if the engine is fully warmed up and situated to read slowly on purpose.

You are better off with a sender under a plug, or drilled and epoxied in very close to it. But in your case a temporary AFR meter may be a better option, get the system dialed in and then you don't have to worry about it in the future.

Fri Nov 07, 2025 5:34 pm

Thanks guys,

I don't have any desire to change heads to accomplish this, so that's a no. I don't mind if the location is a little away from the plug, instant response is not necessary. It's more about watching trends as you drive and noticing when things are not typical. Like oil pressure gauges, none of them are THAT accurate. It's watching the gauges when you drive and noticing when things are not in the usual place. I just was wondering if piggybacking would mess up the signal to the ECU and if there was a gauge out there that would read the resistance from that stock sensor. This would be the cleanest way to do it. A kit for a spark plug sender would probably be the simplest thing to do.

Hans

Fri Nov 07, 2025 7:30 pm

J or K thermocouple extension wire and a volt meter