RX 400h Electrical Gremlins? It Might Just Be a Hidden Water Leak

RX 400h Electrical Gremlins? It Might Just Be a Hidden Water Leak
Apr
29
2025

You’ve got to hand it to the Lexus RX 400h — they built them properly. People love this hybrid SUV because they’re comfy, reliable, and just… solid.

They’re the sort of car that people want to hang on to, and why not?

The problem is, like any car that’s getting on a bit, they’ve got a couple of niggles. One of the main ones we see is water getting into the boot. Nothing major at first, a bit of damp, carpet’s wet — but if it’s left, that water creeps forward and gets into a relay box next to the hybrid battery. And once that gets wet? Bang — warning lights on the dash. Hybrid system fault, red triangle, you name it.

Lexus were clever with the battery itself — they gave it its own little drain. But the relay next to it? No such luck. No drain, no protection. So once water gets in there, it’s only a matter of time.

Now, don’t panic. This isn’t the end of the road for your RX. What we do at New Again is fix the leak properly. We dry the car out, find out where the water’s coming in, and sort it — all part of our Car Water Leak Service

Let me tell you about Hybrid Repair Service LtdMark is an amazing chap we work with who knows these cars inside out. He's mobile so he’ll come to us — or your home if needed — and replace that relay or even recondition the battery if it needs doing. Job done, all in one go. 

Using a random orbital polisher
Here's a 2007 model we have with us at the moment for a leak repair. It's in lovely condition, but has a scuff on the bumper -- that's precisely the kind of damage we can fix.

Of course, you do need to get the leaks fixed before you can repair the electrics — we've done loads of these over the last few years.

While it’s in, we often give them a bit of a refresh too. We can polish up the outside, clean and condition the leather — bit of love and attention, and suddenly, it feels like a new car again. Or at least, like new again. Which is the whole point, isn’t it?

So if you’ve got one of these lovely old RXs, or any of the Lexus Hybrids, and it’s starting to show its age — maybe a few warning lights, or just a bit scruffy — don’t be too quick to write it off. Give us a call, have a chat, and we’ll help you get it sorted. You’ll fall in love with it all over again.

Gary Wray

by
Business Development.

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When bringing your car to New Again, we often ask you to explain exactly the reason for having your car Protected, Valeted or Repaired. Once we understand exactly what it is you are trying to achieve, we will appraise your vehicle using our detailed appraisal check-sheet allowing us to identify areas of concern and tailor specific services that match your requirements and budget.

If you are not sure what service you need and would like to speak to one of our technicians, simply request a callback by filling in the form on our contact page.