Codes P0120, P0441 ,P0300, P0304 and P0305

1999 LEXUS ES 300
190,000 MILES • V6 • AUTOMATIC
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MRSJEBLACKBURN
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Eight codes. two old ( both knock sensors, both have been replaced along with the wiring harness). Yesterday car started to smell faintly of gas fumes. Today car was running fine , then at stoplight it started to idle rough and stumble. And six new codes along with it. P0120, P0441 (shows this code twice), P0300, P0304 and P0305
Sep 12, 2019 at 3:32 PM
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JIS001
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Hello and welcome to 2CarPros. Looks like you have some codes there. When a vehicle has that many codes I recommend you reset the codes and road test to see which ones come back. Most likely the misfire codes will return if there is a fault.

Based on the misfire codes and the engine during order (see image below) I would suspect a faulty coil on cylinder #4.which slows the crank down to possibly give a #5 misfire. Reset the code and swap #2 and #4 coils around. Drive it and see if the misfire moves to cylinder 2. If it does the coil is faulty. As for P0441 most likely you will need a new charcoal canister since the vapor pressure sensor is not sold separately. But the evap system needs to be smoke tested to verify the roll over valves on top of the fuel tank are not leaking. The TPS code, if it returns then you most likely will need a new sensor.

Do the misfire diagnostic first since that is what you need to focus on first
Sep 13, 2019 at 10:20 PM
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MRSJEBLACKBURN
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Well, we did reset the codes. P0304 and P0305 disappeared and in place of those came P0302 and P0303. The P0302 and P0303 had been fixed by mom son about 2 months ago. So we reset it one more time. And everything disappeared but 2 codes. P0305. , Twice. And of the course the knock sensor codes, which had also been replaced along the wiring harness. I'm beginning to think maybe the ECM.
Sep 13, 2019 at 10:46 PM
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JIS001
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The misfire code can set knock sensor codes sometimes. What type of fuel are you using?
Sep 13, 2019 at 11:16 PM
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MRSJEBLACKBURN
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Both knock sensor codes have been there since we bought the car back in January. We replaced them both and the harness. Codes just won't go away. We use 89 octane gas.
Sep 14, 2019 at 12:34 AM
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JIS001
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Welcome back. First we need to focus on the misfire codes. What is the current misfire code you have now since you reset the code?
Sep 14, 2019 at 1:31 AM
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MRSJEBLACKBURN
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2 codes. Both of them are P0305.
Sep 14, 2019 at 1:33 AM
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JIS001
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Okay, remove #5 coil and swap it with #2 coil. Road test. If misfire goes to #2 then the coil is faulty. If not then mist likely the fuel injector is bad.
Sep 14, 2019 at 1:44 AM
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MRSJEBLACKBURN
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Okay, we'll try that next. Let you know what happens.
Sep 14, 2019 at 9:07 AM
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MRSJEBLACKBURN
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Okay, well we cleared the codes one more. P0300, P0304 and P0305. We moved coil packs around and cylinder was the only one.that was having the issue. Bought a new one. No more misfiring and car is running smooth. Cleared codes again, the usual knock sensor codes are showing and it shows that P0441 is pending. How come the knock sensor codes won't clear, even they along with the wiring harness have been replaced. And what does pending code mean?
Sep 15, 2019 at 9:03 PM
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JIS001
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Hello and welcome back. The pending codes means there was a fault detected and the Check Engine light is going to trigger on the next trip. As stated earlier, the pressure sensor is part of the evap canister but the roll over valves are known to leak as well on top of the fuel tank.

As for the knock sensor, if the sensors were accidently dropped then it makes them useless. Also did you use OE parts or aftermarket parts? A big repair like this I always recommend you go OE because those sensors can be hard to get to and OE is your best bet to go with.
Sep 15, 2019 at 9:27 PM
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MRSJEBLACKBURN
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OBD2 keeps freeze framing this. Not sure what it means. Shows the DTC is p0325f. What is that?
Sep 21, 2019 at 7:51 PM
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JIS001
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If it is P0325 then that will be for the right side bank knock sensor. What brand sensor did you use? As stated earlier, if it was accidently dropped it makes it useless. And when you say you replaced the harness which harness are you talking about? The engine harness alone can run almost $3000 let us know please.
Sep 21, 2019 at 9:31 PM
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MRSJEBLACKBURN
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Not sure which brand, and I couldn't even tell you if they were dropped or not.
Sep 21, 2019 at 9:41 PM
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JIS001
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It could have been dropped when they opened it out the box accidently . That is why I personally get paranoid when handling a sensitive part. But ask your mechanic what brand they use. You may want to use the dealer part to solve this issue. Also what harness was replace? If everything is good then the last thing left to replace is the engine control module. Let us know when you have that information.
Sep 21, 2019 at 9:47 PM
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MRSJEBLACKBURN
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Sorry, I wasn't finished yet. We.just ordered new sensors. The wiring harness for the knock sensors was replaced.
Sep 21, 2019 at 9:47 PM
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JIS001
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What brand sensor did you order? Highlighted the right side sensor for you as well.
Sep 21, 2019 at 10:47 PM