Anyone else’s 04 Highlander lose power after replacing the thermostat?

Toyota Truck, SUV and Vans Forum Toyota Highlander
1

After replacing the thermostat in my 04 Highlander (3.3L), I’ve noticed a loss of power under heavy acceleration. If I accelerate slowly, everything’s fine, but as soon as I push the pedal down more than halfway or try to pass, it feels like the gas cuts off. I think it might be a loose or disconnected vacuum line, but I’m open to other suggestions. I’ve seen people mention MAF and O2 sensors in other threads, so I’ll scan it for codes soon. Anyone experienced this before?

2

Yeah, definitely scan for codes. I had a similar issue with my Highlander, and it turned out to be one of the catalytic converters being clogged. Hope that’s not your case, though. The codes will give you a clearer answer.

3

@Zeph
Thanks! I hope it’s not the catalytic converter either. This issue only started after the recent service, so I’m leaning toward something related to the air filter housing.

4

Update: Got a scan, and it showed errors P0101 and P0102. Seems to be related to the MAF sensor:

  • P0101: MAF sensor range/performance problem.
  • P0102: MAF sensor low input.
    Any tips on how to fix this?
5

@lyra
P0102 usually means the MAF sensor isn’t reading enough air. Have you tried cleaning it? Sometimes a quick clean solves the problem.

6

@lyra
Good call, I’ll clean it and see if it helps. Fingers crossed!

7

I’m sure you checked, but just in case—there’s a vacuum hose on the back of the air filter housing that can easily come loose. It’s hard to see, but it causes major performance issues when it’s off.

8

Thorn said:
I’m sure you checked, but just in case—there’s a vacuum hose on the back of the air filter housing that can easily come loose. It’s hard to see, but it causes major performance issues when it’s off.

Thanks, I’ll double-check that. I didn’t notice anything loose earlier, but it’s worth another look!

9

Final update: Cleaned the MAF sensor and cleared the errors. So far, it’s running fine again. I’ll keep driving it to make sure the errors don’t come back. Thanks for the help, everyone!

10

lyra said:
Final update: Cleaned the MAF sensor and cleared the errors. So far, it’s running fine again. I’ll keep driving it to make sure the errors don’t come back. Thanks for the help, everyone!

Glad it’s working again! Keep us posted if anything changes.