The Check Engine light on, rough idle, acceleration jerky, what could it be?

Hi I got a Toyota 98 Sienna LE Check Engine light comes and goes but mostly stays on I don’t know what the code is on the OBD2, I just recently bought a OBD2 diag, but lost it and my home in in a wildfire, in hindsight should have kept it in the van, just bought another on Amazon should have it on Th. Meanwhile it’s running rough at Idle and kind of jerky when accelerating, I"m trying not to drive too much, only other issue has been a really loud whining from the fan belt mostly when the fan is on with defrost but now without it on. I suspect that the Check engine light and rough idle are separate issues from the fan belt, unless the timing is off maybe the timing belt, my guess would be there is a cylinder issue hopefully it’s just plug needing replacing, any thoughts?

You’re playing a risky game driving it while you know something is deteriorating fast. Get the codes from an Autozone if the Amazon one hasn’t shown up. You can Google the codes to learn what they indicate, and post them here.

That’s true, there is an Autozone but it’s not open yet, says opening soon, I just had it worked on I’ll ask that shop if they can do it, but I will have to drive at least a few miles to get to them.

It could be anything from an oxygen sensor to a frozen accessory or combination of problems. I would guess that you have a timing chain instead of a belt. I think your engine is under the floor and your vehicle isn’t worth fixing no matter what is wrong because it could be expensive but I’m hoping to be wrong again.


I would guess that you have a timing chain instead of a belt. I think your engine is under the floor

Could you be thinking of the Previa, which does have engine between the seats rather than out front? I don’t know about chain vs belt on that car.

My 1999 Sienna has engine out front, and a timing belt. There are A LOT of these cars still running around, very few Previas, which says something about owners’ choice for keeping them running. But then, it depends on the OP’s specific circumstances here to decide whether theirs is worth repair.

This forum seems better than carjunky!

Been having a morning start issue. Wasted money on parts didn’t need. Found out a wire went bad and need new computer aka TIPM. Other mechanics confused.

I had Midas fix my Chrysler mini van a month ago. Got oil valves put in at that time. Van had starting issue after oil leak was fixed. Plus a private mechanic said Midas put in a bad spark plug. That’s why van drove funny. I had Midas pay for the tuneup. Still unsure if they caused the start issue or van TIPM just going bad.

As Roadtripper said, that’s the Pevia, I know because I used to own one. It may or may not be worth fixing though depending on what it is.

Yes that’s right I used to own a Previa in some cases they are built far better than Siennas, for one thing the Previa has the Camary engine which is known to be very dependable. So rather than post in general to the replies I’ll just update here, I went to a mechanic got the DTCs and it’s showing 3 codes multiple misfires, misfire cylinder 2. So the mechanic suggested a Tune Up, since one hasn’t been done in the 8 years I’ve owned the Sienna, the problem is while the front 3 are plugs and can be done in like 5 mins, the rear are coils behind the exhaust mani and they are a bitch to do, so I’m looking at a $400 tuneup and that may not even resolve the codes. As this video shows it could just be a bad #2 ignition coil so that’s worth considering. I’ve made a tentative appointment with the shop for next Wed. but there is a recommended reliable mechanic right by were I’m staying that may do it for less so I’m going to go see what they have to say. I’'ll keep you posted as I find out more. Any idea what the size of the wrench is to remove the plugs cover?