Corolla Preheating Lamp Issue

Hi, I'm having a weird issue with my 2006 Toyota Corolla diesel. The preheating lamp on the dash just won't switch off, and the check engine light is now illuminated. Also, I've noticed some smoke when I accelerate, which is definitely not normal. I've checked the basics - fuses seem fine. I'm suspecting it might be related to the engine preheat system, possibly a defective preheating unit or maybe just a bad connection somewhere. I read that a faulty cable or plug connection could cause this. Anyone else experienced this? Feels like a relay stuck in the 'on' position, like a faulty switch.

4 comment(s)

I had a similar issue on my Corolla. Check the cable and plug connections to the preheating control unit. Make sure they are clean and properly connected. Have you scanned the car for error codes? That would give you a more precise idea of what's going on.

Thanks for the tip! Where exactly is the preheating control unit located? And did your car also have the smoke issue when accelerating? Just trying to confirm if we had the exact same symptoms. I will scan for error codes as you recommend.

Yes, I had the smoke issue too. The preheating control unit is usually near the engine block, but I recommend taking it to a workshop to confirm the diagnosis and avoid damaging anything. They can pinpoint the issue quickly.

I took your advice and got the car scanned. Turns out it was a defective cable to the preheating control unit, just as suspected! The workshop replaced the cable, and the total repair cost was 95€. No more preheating light, no more check engine light, and no more smoke. Thanks for your help!

Join the discussion now: