Hybrid Passat Won't Start After Prior ECU Repair

Had similar symptoms with a 2019 Passat GTE hybrid last month. The initial engine fault diagnosis pointed to the ECU, but the real issue was much simpler, corroded battery terminals causing poor connections. When the main battery connections are compromised, hybrid systems often show misleading symptoms. The dashboard powers up because it needs minimal power, but the starter and hybrid system require solid connections for full current flow. The key check points should be: Battery terminal corrosion, Cable connection tightness, Ground strap condition, Battery health test A proper engine diagnostics scan showed no actual ECU faults in my case. The fix required cleaning the terminals, replacing one corroded cable end, and properly securing all connections. This resolved both the starting issue and prevented potential damage to the hybrid system. Given your previous ECU repair, request the workshop to specifically check all battery connections before assuming its related to the earlier work. Poor connections can trigger multiple system faults that may appear as ECU problems in initial scans. This is typically not a serious issue if caught early, but leaving it unaddressed can lead to damage in the hybrid control systems from unstable power supply.

Thanks for sharing the solution with the battery terminals. My GTE had similar starting problems which I first thought were related to engine software errors. Did you remember roughly how much the repair cost? Also curious if youve had any other starting issues since getting it fixed? My mechanic quoted 450€ for an ECU diagnostic but it sounds like I should have them check the battery connections first. Starting to think they might be trying to upsell me unnecessary work.

After getting the battery connections fixed, my GTE has been starting perfectly without any engine surge or stalling issues. The total repair came to 155€, which covered cleaning the terminals, replacing a cable, and checking all connections. Much more reasonable than an ECU diagnostic. The workshop found the exact problem through basic engine diagnostics, no complex ECU work needed. The engine light never came back on after they properly secured the battery connections. This fix resolved all the starting problems completely. Would definitely recommend getting the battery connections checked before paying for expensive ECU work. From my experience, what looks like complex engine control malfunctions often turns out to be much simpler electrical issues. The battery terminal problem is pretty common on these hybrids, and fixing it properly the first time prevents further starting issues. Since the repair three months ago, the car starts reliably every time with no warning lights or faults.

Based on your advice about the battery terminals, I went ahead and got a second opinion from another workshop. They immediately spotted heavy corrosion on the main battery connections, just like you described. The fix only cost me 140€ including a full connection check and terminal cleaning. The engine starts perfectly now, no warning lights or starting issues since the repair last week. What really bothers me is that the first workshop was pushing for expensive ECU diagnostics when a simple check would have revealed the real problem. Their 450€ quote seems ridiculous now compared to the actual fix needed. The new mechanic also showed me exactly what was wrong, explaining how corrosion affects the fuel injection and starting systems. This kind of transparency makes such a difference. Really glad I asked for advice here before spending money on unnecessary repairs. Looking forward to trouble-free driving now that the actual issue is resolved. The whole experience taught me to always get a second opinion when dealing with check engine problems, especially on hybrid systems.