Toyota Prius Forum banner
1 - 7 of 7 Posts

· Registered
Joined
·
6 Posts
Discussion Starter · #1 · (Edited)
Hello, all. I bought a 2002 Prius when I was basically desperate for a car. Got ripped off by a guy who told/showed me all the great features of a Prius but conveniently forgot to say the cat(s) had been stolen.
I’ve been looking on/off for a week trying to replace what was taken. I’ve only found a front cat and the “air valve”, not what appears to be a 2nd cat—one article called it an “HC adsorber”. Toyota dealer and local muffler shops said $3500 to replace. Separate front cats seem to go for $200 up (must be CARB-compliant, as I live in CO). Air valve is $300 from dealer. Haven’t found the adsorber. Neither has any local auto parts store. And CO emissions said it’s against federal laws to sell used cats.

Does anyone know how to find a whole assembly? I’ve seen them for $60 to 150 for 2004-2009 Priuses.
I’m hoping one of those would fit on this car, and work as a temp solution.

Thanks!
Frustrated in Fort Collins
 

· Registered
Joined
·
3 Posts
Hello, all. I bought a 2002 Prius when I was basically desperate for a car. Got ripped off by a guy who told/showed me all the great features of a Prius but conveniently forgot to say the cat(s) had been stolen. I’ve been looking on/off for a week trying to replace what was taken. I’ve only found a front cat and the “air valve”, not what appears to be a 2nd cat—one article called it an “HC adsorber”. Toyota dealer and local muffler shops said $3500 to replace. Separate front cats seem to go for $200 up (mistCARB-compliant, as I live in CO). Air valve is $300 from dealer. Haven’t found the adsorber. Does anyone know how to find a while assembly? I’ve seen them for $60 to 150 for 2004-2009 Priuses. Thanks! Frustrated in Fort Collins
Does Colorado actually require that you have an OEM Catalyst? That upper cat with the HCAC might be worth getting a hold of. That "Air Valve" is very hard to come by, and if you actually find a whole Cat assembly for a Gen 1, new from the dealer, you are very lucky to find a dealer with old discontinued stock. The cats were stolen off my 2003 Gen 1 and I did a very in-depth search for the OEM Gen 1 cats from Toyota, and used, and aftermarket. I discovered that the Cat Assembly is now a discontinued part. The search for used assemblies found either junk or way over-priced listings, and there is no aftermarket unit made that has the HCAC unit on it. The 2002 to 2009 Cats fit the Gen 1 perfectly, but without the HCAC, I picked up a Honda Goldwing Cruise Control Vacuum Pot and installed it on the vacuum line. It adequately simulates that action of the HCAC vacuum pot. Otherwise, you will get trouble codes for the missing HCAC of either the vacuum being open if you do not plug the line there, or for the vacuum being closed if the line is plugged but there is no vacuum pot action. The ECU can sense that there is no variation in the HCAC vacuum pot and so it throws a trouble code. I found an aftermarket EPA approved Cat Assembly for the 2004 - 2009 through eBay. It fits perfectly, and the tailpipe emissions readings are well within CARB requirements. Getting close to 2 years with it and there have been no trouble codes and the absolutely no change in the emissions readings, which I recently got just for curiosity's sake to monitor the performance and quality of the aftermarket assembly. I hope my story here has been helpful and that you get a good Cat assembly. That 2002 Gen 1 is quite a special car. My 2003 has quickly become my favorite car. It is fun, reliable, economical, and a joy for me to drive around in the mountains.
 

· Registered
Joined
·
6 Posts
Discussion Starter · #3 ·
Bruce:
Wow, thank you for the comprehensive reply!
I had already ordered a cat & resonator assembly from Amazon that fits 04-09 Priuses,
thinking that it would give me two cats or one plus a resonator. Intuition said it would fit.
I’ve seen lots of these assemblies, but no explanation of what they are. This one is EPA, so
could work in parts of CO that don’t require passing emissions before getting a plate to drive it.
That’s my PlanB—sell it in one of those or in WY who has less-stringent regulations.

I talked to an CO emissions tech yesterday, but he didn’t say if they require documentation of cat being
CARB-compliant. If they don’t, and it does pass the test (with the air-valve you’re saying could be
cleverly replaced with the Gold Wing part), then I perhaps could drive it on the Front Range
(emissions tests are required). I have 5 more weeks to get the right set of parts to make it pass
emissions, or sell it where it can run quietly in a non-emissions area. First set of parts will be
here tomor (cat assembly and new O2 sensor). Thanks again for crucial info to help my
waning optimism.
Nov8v

PS. I’m glad to hear it’s a worthwhile car! I liked it a lot when I drove it. Quick handling, regen braking,
great stereo. And [CkEng] light was off. Thieves know how to clear those codes, I recall now.

This reminds me that it wasn’t running on the EV battery until yesterday. It’s been having idle-speed
problems, alternately revving & idling. I assumed that was related to the lack of air valve & cat.
I’ve had that on other cars, and cleaned MAF, TPS, idle air valve, etc. to fix it easily.
An auto parts guy told me that it could also be due to a low batt voltage. It has a high-capacity starter
battery in the trunk (12 V, and I assume a deep-cycle marine type). It drained overnight on Sunday, and
so I put the new battery from my dead Kia in parallel with it (jumper cables), and it started running
in EV mode when “almost coasting” or stopped, or at low speeds in parking lots. I have a manual, and
I will read about this tomor. But any insights on this before I spend days on research—if manual
does not explain it well?

Thanks again, sir. You’re a gentleman and a scholar. 👍🏼 🙏🏼
 

· Registered
Joined
·
3 Posts
The reason for the lack of running in EV is almost certainly due to a bad 12volt battery and/or a bad terminal or ground point.

The 12volt battery does not turn over your engine as in a traditional car, your car does not have a starter, The HV battery and HV Motor are what starts the engine.

What the 12volt battery does is boot up all of the ECUs and support some accessories.

If the rested battery voltage is under 12.3 volts, the ECUs cannot boot up properly, which can cause all kinds of codes and false codes.

Also, when the battery is bad with low voltage and/or bad resistance, and the HV Battery, Generator, and Inverter are what charges the 12v battery, that bad battery is causing the HV system to continually have to work to charge it.

This, as with any draw, will cause the engine to run more often, maybe even constantly.

For instance, if I run my A/C fan on high with the A/C turned on, that creates enough draw that my engine runs much more constantly.

When I slow down or come to a stop and turn off the fan and A/C, the engine turns off.

The system on this car is designed to balance the engine and the electric to run at its most efficient, so if you are watching your power screen as you drive, you will see the screen showing it running on electric to engine + electric to engine in what looks like random ways, and possibly in ways that don't make sense to you. Don't worry, the system is doing its job.
 

· Registered
Joined
·
6 Posts
Discussion Starter · #5 ·
Hello again:
I installed the new cat assembly last Saturday. It’s for an 04-09 Prius, but fits into this car perfectly. $50.

Car runs quieter. And as long as the aux batt stays charged, it runs in EV mode when it can. Haven’t even connected the O2, whose cable the thieves cut.

Connecting the Kia batt occasionally seems to help the Prius batt stay ~12.6V. I don’t keep the Kia batt connected all the time, because Toyota dealer said a Prius is set up to charge the gel aux batt and has diff charging methods than for lead-acid batts. Could cause nasty fumes in passenger compartment

I no longer curse this vehicle. I pat it gently on the dashboard, thanking it and saying a prayer of gratitude.
I liked from the moment I got behind the wheel—except when it revved/idled annoyingly

Thanks again, Bruce. (y)
You improved my life! :)

ImNov8v
PS. Do you have a part number for
that Goldwing valve/pot?
 

· Registered
Joined
·
6 Posts
Discussion Starter · #6 ·
I replaced the downstream O2 sensor. It immediately used the EV-drive instead of ICE-drive
while in Reverse. Nice surprise.

I took it to the state emissions testing place, and it PASSED. I didn’t think it would, because
I just plugged the vacuum tube (used to go to that “air valve” that Toyota wants $300 for).
That’s the one that BruceBerquist_3929 replaced with <a Goldwing pot>. I didn’t look for it,
because I couldn’t fathom how a “pot” (potentiometer?) could be connected to a vacuum tube.
Maybe there’s an electrical connection that got cut when the cat/adsorber/air-valve were stolen?

I should read the dang manual. I’m selling my house now, and dealing with a family crisis, so
I barely have time to fiddle with this a couple hours every other day.

I thought at first the lack of the air valve was causing revving/idling swings in ICE rpms.
But that wouldn’t explain how rpm-swings lessen/stop after driving the car a few minutes.
I’d guess it’s related to the battery not often charging to more than 12.4V.
Any guesses about this?

I went to the dealer for help, and they said the next opening is 5 weeks away.
I did read some pages of the manual that talked about a Toyota Hand-Held Tester (THHT)
and an OBD-II tester. The former is more comprehensive, but looked to cost $600 on ebay.
I can buy an OBD-II for $20 on ebay or Amazon.

I bought a battery charger: 8A, but slows to trickle-charge when batt is almost charged…
and the box said it works with AGM batteries. I kept it on the battery all night last night, and
the voltage this morning was about 12.7V. But it soon fell back to 12.4 after I’d driven
to town and back (20 miles RT).

I found a gel batt that’s affordable, but as I said before, this batt (a Toyota part, saying “5-22-22” on it)
gets discharged if I don’t drive car for 2 days. Batt also self-discharges while disconnected, albeit
a little more slowly. The charger I think has a pulse-mode, which many say can repair problems
in the battery like build-up on plates that cause high resistance. I’ll charge it overnight 2-3 more
nights to see if that brings back some of the higher voltages in mornings—and after driving 30 min.

So maybe this is my big question: if I replace the gel battery, is that likely to fix the
revving/idling variations? Or is that caused by the lack of that air valve? Or is it the
charging circuit that’s faulty? (not charging the batt past 12.5V) I know this may be a lot to ask,
being as the car is a 2002. I’m mostly trying to keep it out of the salvage yard for 5 more years,
and will likely sell it because I won’t need a car over the winter—hopefully—and it’s beyond
my limited auto-mechanic skills and time… and I don’t even have a garage. I’d hate to sell it
without fixing this big problem! I’ll lose money on it, but at least it’s still on the road.
Do Prius lovers sometimes buy these older models with the same hopes?

Thanks!
 

· Registered
Joined
·
25 Posts
We bought a 2010 Prius about 3.5 years ago, excellent condition, with low miles. So far, I've replaced:
Traction battery $2440, 12V battery, $200, tires, $700, and had the EGR system completely purged, with 2 new parts, $1800, rear brakes done, $200. It hasn't exactly been the cheapest car to drive, but I never worry about it breaking down on us. The oil is changed every 5,000 miles. The gas mileage ranges between 47 and 52 mpg.
Usually, when a Prius owner sells or trades one off, they consider it to be at the point where it's gonna start losing money for them.
 
1 - 7 of 7 Posts
Top