Madartsoft

After drove over 200 miles. The P0420/P0430 is back! It's not often as in a past but again I see the codes. Car runs smoothly but even after 200 miles the LTFT shows -18.8 on both banks at idle and -9 when driving quite fast. I think is to check fuel pump pressure but I had not this issue with old MAF. The new MAF sensor is China cheap replacement £21 maybe it's something wrong with the MAF.

I made readings and tests again today. It seems that all codes disappeared, I made over 130 miles. Also, I noticed fuel consumption improves from 28 to 32 mpg (I tested the usual trip). Now the Long fuel trim shows -20 which means that the PCM removes the fuel. Thanks ColinBarber, probably the PCM is learning and the values are so high. I'm going to disconnect the battery but it should learn also without this step I guess. Before changing the MAF the error code appeared after 10 miles drive but now it's over 130 and no codes (no pending codes) ! I'm guessing disconnecting the battery will clear all settings.

Hi, I replaced the MAF and still, the same issues P0420 and P0430 as pending now. I also noticed one more thing. I have Long Fuel Trim +10.8 on both banks. I wanted to replace two rear O2 sensors but decided not to do this as ColinBarber suggested it must be something like a leak somewhere. Is there any good method to check the intake leak?? Also, I don't know if it's important. I attached scan tool and on idle (when batteries are charging) the idle is about 1000 rpm. Is it not too high?

Yes, hybrids are exempt from emission test but I checked also independently the emission and they checked it when I pressed the accelerator (the engine then revs).

Today in a garage someone made a visual inspection of the exhaust and said that everything is alright. No exhaust leaks. One more thing to check is MAF. It's a simple device I cleaned it already. I'm going to check it using multimeter but when driving the car I can't see any issues and I doubt it's a MAF (errors could appear if it's faulty). Also, I doubt two o2 sensors failed at the same time. I would avoid use o2 spacers because I prefer to find the real source of the problem but in this case, is the solution. Maybe there is an issue in the intake manifold. Forgot to add that I had an emission check and it was alright.

Thanks, I will look at the Y joint and later A/F sensors but as you mentioned it's unlikely that both A/F sensors are faulty at the same time.

Hi, I noticed that both codes P0420 & P0430 appears (in the same time) more frequently than few months ago. It happens when system is in Closed Loop (warmed) but not enough (just 5 mins) drive on A road. When the car is fully warmed (drove 15 miles) I cleared the codes and when the engine is still warm enough (driving a lot) then codes doesn't appears but when I allow the engine to cool down, the next time the engine is warm the codes appears. I cleared the MAF sensor already, changed air filter. I also read the O2 sensors readings but voltages jumping a lot from 0.1 V to 0.8 volts. Other readings seems to be ok such fuel trims (Short -2.6 and Long 0.7). I also checked A/F tests (rich and lean tests) and the delay is avarage 1.5 sec it seems that the cats are still working ok. There are no misfires. It's strange that the possibility faulty cats started exactly the same time. Next step will be checking the exhaust leaks but it also strange that there could be leak in both banks. Also, I had few trips (each over 1200 miles) on German motorways driving over 80 miles per hour and no sign of overheating or coolant leaks, changes in engine oil level. I guess, if there will be any problem with intake manifold then could be overheating or coolant leaks??

Hello Herbie, Thank you very much for the diagram. Partially I manged how it should work but now it will make it more simple. Have you noticed any issues connecting the relay to EFI ?? Thanks and regards Sylvester

I think in rx400h fuse (marked red) is EFI. It's 10AMP fuse, the relay coil needs 150mA so should be fine I guess. Could you draw the diagram for two relays please?

Hi, I'm trying to install DRL in RX400h and looking for +12V power source in the engine compartment. The power should be only when ignition key is in position ACC or engine on. I checked in fuses box and there is 12V but even if the engine is off. Regards

Hi, I'm trying install DRL in my RX400h and can't find the source of +12V. The +12V should be only when engine is on or ignition key is set in position ACC. Regards

Could someone explain me where are located the banks? Is the O2 sensor bank 1 and 2 located after cat? I checked OBDII readings. As explained on the video the bad cat, the waves on O2 sensor 2 should be similar to A/F sensor 1 but I have a question. If I press the accelerate pedal then the O2 sensor 2 (after cat) should change or should it have the same level?

Thanks. I just checked the code which goes off itself and it was P0430 (previously P0420 and P0430).

Hi, I got recently error code P0420 and P0430 in the same time. The MIL was on. I cleared the code and after 300 miles it comes again. I drove approx 100 miles and the MIL goes off itself. Any ideas what is wrong? I read that it can be catalyst converter which is bad option. The car is 126K miles now.

I also have similar problem. the warm/cold temp is ok but it seems that it struggling to find the correct position and some strange noises are generated. The sound changes when switch manually the air direction. So I guess it's a mode servo. The Lexus quoted £231 inc. VAT. for part.