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Shortly after buying my 04 VW Golf, the engine check light came on indicating a fault in the NOx sensor. The engine error code is as follows:

17478 - NOx Sensor (G295) Heater Control 

        P1070 - 001 - Short to Plus - MIL ON

The sensor is actually pretty expensive to replace, around £400. I'm wondering if it's actually necessary to fix immediately. The engine check light came on not long after I bought the car, so I'm guessing I bought it faulty. But since I haven't drove the car pre-fault, I have no idea if it had an effect on the power of the car, or fuel consumption, and whether or not it's an urgency to fix.

Any advice/suggestions are welcome.

  • I think I got this error once when it was -25C outside and battery was low and started the car. Now I am not sure if the error was the NOx sensor or O2 sensor but it appeared immediately when I started the car. I think if this was faulty, the error would have come quite quickly, not after a short while. – Evren Yurtesen Oct 22 '16 at 21:54
  • @EvrenYurtesen, I'm not quite sure tbh. With my case the sensor itself was faulty, not the connections (the final connection was a little rusty, could have been that but I'm not sure). Ended up replacing it with a second hand NOx sensor which works fine so far. – Taha Oct 25 '16 at 13:25
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The sensor operates at a very high internal temperature (circa 400 degrees C).

There will be either three or four (there were four on my 1997 Golf) wires going into the sensor. One set of wires are for the actual reading and the other are for the built in heating circuit.

On my Golf, when I had this exact same code, one of the wires from the heater circuit had frayed and snapped. I simply re-attached it and all was well. No needed to change any of the expensive sensors. The only downside is that access to the wiring harness was poor so a relatively simple job became quite fiddly.

The reason I had to fix ours was that the emissions test was high. After it was fixed, throttle response and fuel consumption both improved.

  • Could be internally burned out as well, happens to O2 sensors. – I have no idea what I'm doing Mar 22 '16 at 13:29
  • Thanks! Will check the wiring on the weekend and see how it goes from there – Taha Mar 22 '16 at 18:12

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