milellie11

iTrader: (5)

I have an 02 GS430 with 105,000 miles. Just got my Cats replaced from a muffler shop because Lexus and an independent shop both said that they pulled codes P0420 Catalyst effiency below threshold.
Pick my car today and 5 minutes after driving, the CEL light comes back on and the car starts acting as if it's running very sluggish/ like bad gas or something (been doing this the past 2 weeks). Of course i'm very pissed. Take it back to the shop and they say that maybe i never needed my Cats replaced. They scan the code and it says P0325 Knock Sensor.

Can anyone help me out? I've dumped so much money into this car it's not even funny. It's a headache and i doubt if i will be buying another Lexus. I was sold on the "reliability" but now i laugh when i hear it and think of what i'm going through with my car. Please give some insight. Thanks

milellie11

iTrader: (5)

bump for any help possible...thanks

BossGS4

iTrader: (2)

• reset ECU
• check all the electrical connections. take them apart and re-connect
• have you ever changed your MAF sensor ?
• have you changed the fuel filter ?

milellie11

iTrader: (5)

Have never changed the MAF sensor or the fuel filter. Will these things be related to what i'm experiencing?

milellie11

iTrader: (5)

Check engine light is off and car runs fine at times, then all of sudden loses power????

Debonair

That is an odd DTC, are you sure that is what they were getting? I can not find that on the official list of DTC's for our cars.

Here is the generic definition for that DTC:
P0235 - Turbocharger/Supercharger Boost Sensor "A" Circuit

milellie11

iTrader: (5)

Sorry Debonair, but i mistyped the title to the thread. The actual code is P0325. The guy showed it to me from the OBDII scanner.

Debonair

P0325 is the Front Side Knock Sensor as the shop told you. This can be caused by a bad Knock Sensor, bad wiring from the sensor to the ECM, or a bad ECM. Most likely it is just the sensor.

From the location (#4 on the pic below) it looks pretty easy to get to. The part is available real cheap on RockAuto ($70ish) if you need to go that route. Otherwise try all your local parts places, Lexus parts departments, or Sewell ($190ish).

I don't know the history of your car (I too have a 02 GS430) but for whats its worth my personal idea of a reliable car is one that does not leave me broken down on the side of the road. If that costs money every now and then I'm OK with it. Cats go bad on all cars too, not just ours. They are expensive for everyone. Spending the money still sucks though.

milellie11

iTrader: (5)

First off, i'd just like to give a big thanks to you for responding. Second, props to you for such an excellent concise and helpful post. You gave me everything i needed to know, gave some options on where to buy the part, even provided a wonderful diagram on where the sensor is located. And you didn't have to write a narrative, you gave your answer in a concise straight to the point way. You are a perfect example to all posters in forums striving to helpful

I bought the sensor this morning from Sewell online, came up to about $137. Great price to me. My friend who's a mechanic and owns a LS400 will be able to install for me later in the week. He was worried that it would take a while because he was thinking that he would have to remove the manifold. I will show him the diagram which should be helpful.

I bought the car used with 41,000 miles on it and now it has 105,000 miles everything stock. Has never been abused or neglected. I'm just frustrated because as soon as i paid the car off(had about 95,000 miles on it) thats when things started to mass fail. Had to replace Mark Levinson amplifier, rear door lock actuator, drivers side window stopped working so door ecu computer replaced, car rode like crap and wouldn't keep alignment and abnormal tire wear so all control arms/ball joints/tie rods/shocks replaced. (Front end still squeaks and makes a noise while braking Then, CEL pops on and off, so I take it to Lexus and they read code P0420 and state that i need both of my Cats replaced($2800). Hoping they were lying to i took the car to an independent shop and they said the same thing. No way around this because the car eventually starts to lose power etc., so i get the Cats replaced (OEM Cats) from a muffler shop thinking that should clear the CEL. 5 minutes of driving and the CEL pops back on as it alway has and the car starts driving like crap all of a sudden like it's been doing for the past month. Take it back to the muffler shop, they scan the code and voila, they show me code P0325 Knock Sensor Circuit 1.

Guess you may see why i am frustrated because all of the above happened within the past 10,000 miles. I know the car hasn't left me stranded, but the above issues sounds like a scenario from owning a German automobile rather the ever reliable Lexus. Audi's BMW's and Mercedes most likely won't leave you stranded either, but they sure do have a lot of nagging little issues that will make you want to pull your hair out. This is exactly how i feel with my GS.
I might as well have a car payment the way i'm dumping money into it every month or so.

Debonair

Thank you.



Well I think he is correct. Both manifolds do have to come off. Looks to be a 3.5 hour job based on the labor guide i checked. If he is familiar with working on cars this will probably go faster. Be sure to supply him with a 6 pack or two.

I totally understand about the timing of having to spend money on repairs sucking. When I paid off my Durango, which I bought new, the transmission went out. That was not a fun one. You have had a serious run though which I can not compete with with any of the cars I have had. Hopefully this is the tail end of it.

Debonair

Looks like its my turn. Got a P0325 yesterday, cleared it, and it came back this morning. Time to order the part and pull the manifolds off.

DWCOILE

Hey guys. I too have a 2001 GS430 and the same code is popping up sporadically, (p0325) usually on my commute to work or home. I will be the first to tell you I love these cars but the wiring harnesses and connectors are amongst the worst in the industry. Clips break on the connector's and they seem to fray after so many years. I have experimented with this issue i.e. replaced the sensor, added a ground wire to the block on the left bank under the intake manifold, triple checked the wiring and connector and still the light comes on here and there. I am very confident it is in the wiring harness. Either replace the complete harness or at least the wiring to the knock sensor it self. It isn't too bad to repair. I did it in about an hour, Granted I own a repair shop.

Debonair

Thanks for the input and experience. I will be replacing the wiring to the sensor for sure. I am confident its tendency to fail is the reason all the part suppliers offer it along side the sensor itself. And at $20 its worth I think.

Are the manifold gaskets a reusable type?