The dreaded 16500 fault code

**Hans** · 25-04-2018, 11:37 AM

Hi all,

I seem to have come up with fault code "16500 engine coolant temp sensor (G62) implausible signal" on my Polo Gti.

Took it back to the dealer where I've just bought it. He gave it to his mechanic to fix. The mechanic "replaced the temp sensor and the thermostat".

Two days later, the fault code is back. This has me wondering:

Which sensors does the ECU cross-check to determine if it has a viable reading?

Is it G62 and G83?

Also, I ran a graph of the G62 output with Intake Air Temp as a baseline at the start of it, the sensor seems healthy.

Thanks in advance for any input.

**sambb** · 25-04-2018, 07:04 PM

pretty sure that's the fault I had recently. Mine was the sensor in the coolant line that leaves the head (passenger side). Is that the one they did? Have a look and see if it looks new.

**Hans** · 25-04-2018, 07:45 PM

I'm suspecting they replaced the wrong one. Mechanic is maintaining he changed the "temp sensor with the 2 pins". G62 has 4 as far as I know. That would mean he did G83 if this car has one. And it would explain why the fault is recurring.

**sambb** · 26-04-2018, 01:16 AM

How to Replace a Temperature Sensor MKIV VW/Audi, Jetta, Golf, 1.8T DIY | AxleAddict

OEM VW and Audi Green Coolant Temperature Sensor 059919501A - Deutsche Auto Parts

this is the one I did. Its a 2 pin. are you getting the temp gauge sitting in funny spots?

They may have done the temp sensor in the radiator.

**Hans** · 26-04-2018, 09:08 AM

Seems very much to be a 4 pin. https://www.amazon.ca/059919501A-Coo.../dp/B00UHCRZA4

**Hans** · 26-04-2018, 09:12 AM

And yes, the temp gauge is not being very realistic.

**Hans** · 26-04-2018, 11:26 AM

Alright, watch me eat my words: The G62 sensor on this particular car IS 2pin. What's more, apparently the temp gauge is supposed to have the huge deadband that I've been observing. The fault code hasn't come back since I cleared the fault.

This leads me to suspect that there may have been a bit of a bubble somewhere after the faulty sensor was changed, and that is possibly the end of that.

**sambb** · 26-04-2018, 11:39 AM

yeah if the temp gauge is back to normal, and the cleared fault isn't coming back within 2 days you'll probably be good. Depending on how much coolant they lost when they did it make sure the coolant bottle hasn't dropped.