2016 polo 1.4 tdi Non-start

[Chris1989]

Hi I have a 2016 polo 1.4 tdi (cusa), I bought the car as a non-runner told dues to a failed turbo after inspection the turbo had indeed failed and the shaft was broken, I replaced the turbo and checked and cleaned all associated parts but when trying to start the car it would turn over but not fire. The car will run if I spray brake cleaner into the intake unit I stop. I carried out a Diag scan and the only code present is p0562 (system voltage low). I replaced the battery but the code is permanent and won’t clear, I’ve checked all fuses and relays also replaced the Ecu with a cloned one but still can’t get the car to start. I’ve noticed that the lift pump in the tank isn’t priming or running on cranking but it can be operated via out put test. I’ve check to see if the injectors are being trigged and they don’t appear to be so I’m sure it’s a fuelling issue but im running out of ideas on what the cause of the problem is?

[ciclo]

Hi
Alternator?

[Chris1989]

I will check the alternator today I don’t know if that would cause a non start but definitely worth me checking

[ciclo]

As you already likely know, in addition to checking the battery terminals with a multimeter, make sure the power cable (G) and large fuses are in good condition.
hmm... also check the alternator cable connection to completely rule out that the fault comes from here.

[Chris1989]

Yes I’ve checked all main the fuses at the battery fuse box, I’ve checked the battery ground wire and the other engine bay grounds. I will check the power cable from the alternator today.
I did notice that when I get the car to run on brake cleaner I can then clear the p0562 code but it will then return after trying to start the engine normally and then won’t clear

[ciclo]

Is it manual or DSG?
I ask so we know if it's possible for you to do a "definitive" test.

The fact that code P0562 can be cleared when the engine is spun using brake cleaner () but returns immediately upon attempting a normal start confirms 100% that the problem is caused by a massive voltage drop at the exact moment the starter motor engages.

Do not look for fuel or ECU issues, the car is not injecting because the starter motor (or a faulty main cable) is causing a momentary voltage drop whenever you turn the key, triggering the ECU's lockout protocol.
The problem could be due to a shorted starter motor or a main positive or negative cable with extremely high resistance, or, the main relay might have burnt internal pins, causing the circuit to cut out under load, it depends largely on how insistently the previous owners tried to start the engine.

[Chris1989]

Hi the car is a manual transmission, thanks that does make sense what would you advise I check next?

[ciclo]

Try starting the car by pushing it, rolling it downhill, or towing it with another vehicle (not recommended if the driver does not have the necessary skills), with the ignition switch set to "ON".
If the car starts immediately upon releasing the clutch, the starter motor is faulty and needs to be replaced.

A quick reminder: Ensure the power and ground cables are securely connected and in good condition, we want to avoid any cable that was handled during repairs coming loose or not being properly secured.

[Chris1989]

Ok thanks il double check all the leads and try to tow start it tonight and let you know how I get on