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Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 21495
Experience:  BEng hons Mech engineering, in auto industry 22 years
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What is the fix for fault code P1723 on Audi Q5

Customer Question

What is the fix for fault code P1723 on Audi Q5
Submitted: 9 months ago.
Category: Audi
Customer: replied 9 months ago.
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Customer: replied 9 months ago.
Glow plug light sometime comes on after driving for several minutes on my Audi Q5, had car checked and was told read fault code P1723 starter interlock circa open.What does this mean and how can it be fixed.
Expert:  Matt replied 9 months ago.


to get this code then either ;

the starter has failed or there is a power supply problem to the starter activation circuit. Or a starter ground circuit problem.

The starter has three things it needs to crank There should be a battery cable secured with a 13mm hex nut. There should be one 2.5mm wire going to the #50 terminal. This wire is the crank activation wire and is simply held on by pushing it over the spade terminal. And lastly a ground path going from the starter to block, to grounding strap, to body, to battery negative cable, to the battery.

I suggest to check at the starter #50 terminal (starter control) for battery voltage when the ignition switch is held in the start position.

This is the small wire pushed on the spade connector. The only other wire to the starter is the positive battery cable.

If you have at a least 11.5 volts, move the volt meter lead to the Big battery wire. With the key still held in the crank position you should have very close to 11.5 volts.

Now move the volt meter terminal to the starter case you should have 0 volts. This would confirm a good ground path. If you had 1 volt or more, the ground path is the problem. If you have a min. of 11.5v at the #50 terminal and the battery terminal of the starter, and less than 0.5v at the starter case, the starter has failed and requires replacement. If you have voltage, but less than 11.5v or more than 0.5v at the starter case, get back in touch with me and we can proceed down that path. You can also apply battery voltage (11.5v min.) to the #50 terminal and confirm that the starter is NOT the issue. This also confirms the ground circuit.

If you DO NOT have power to the #50 terminal the cause is likely a failed ignition switch, starter interlock relay, neutral safety start switch.

I suggest you try turning on the key, apply your foot to the brake, move the shifter from park to neutral and try starting the vehicle in neutral.

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    Mechanical Engineer

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    BEng hons Mech engineering, in auto industry 22 years
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