lexisaurus

Hello folks.


Can anyone offer any suggestions on this. I have an engine warning code, trac and flashing VSC.

90K miles, engine runs and starts and idles smooth as butter. On top of this mileage is bang on (premium fuel apx 22-23/18-19 mpg)

I'm thinking possible bad ECU since there are no symptoms... or is it possible to have all these "problems" and not notice? For sure live scan is next.

P0031
Oxygen Sensor Heater Control Circuit Low Bank 1 Sensor 1

P0351
Ignition Coil 1 Primary/Secondary Circuit

P2195
Oxygen Air/Fuel Sensor Signal Stuck Lean Bank 1 Sensor 1

P0172
System Too Rich Bank 1

P0175
System Too Rich Bank 2



Thanks for any suggestions!

BlackLexRX

When o2 sensors go bad, sometimes you can't feel it. That was the case in my last car anyway, but when I replaced it, MIL went off. One thing that will happen with bad o2 sensor is a decline in MPG, at least that was my experience. p0172 and p0175 will most likely go away once you replace your bad o2 sensors. As for a bad ignition coil, you are lucky if you don't feel that one yet as it can create misfires and very rough engine operation.

lexisaurus

Thanks. So you think trust the codes even though no symptoms it sounds like....

BlackLexRX

Well, you can keep driving it of course, regardless. One thing you can try is unplug your negative battery cable for at least 30 seconds then reconnect. This will reset your ECU, and if your lucky MIL will go away. If it comes back, reread the codes and proceed from there. Disconnecting your battery will reset everything though which means your auto settings for seat position, window, moonroof, power hatch, and the like will have to be re "initialized", which is easy to do, just consult your manual. Try that, if codes come back, they're probably legit malfunctions.

05RX330AWD

Agree with BlackLexRX, I usually erase codes when they appear with a OBII scanner, at times they do not return.

RedGemini

It sounds like you have a code scanner. If so, use that to reset your codes. The battery disconnect will provide no more benefit, but will be a pain to reset everything due to the disconnect.

lexisaurus

Yes exactly thanks

All lights/codes come back within 30 seconds of running engine after clearing. Again there are no symptoms with respect to how the engine starts/idles/runs and MPG seems normal. Have any of you had this scenario before?

thx!

nwfsnake

Bad O2 sensor.

BlackLexRX

Couple of them sounds like. Which is odd to have them go on both banks simultaneously.

lexisaurus

So let me get this straight... I have the least experience here but am the only one who finds it highly unlikely that 2 X O2 sensors and a coilpack are bad despite no issue with engine performance or MPG?

OK tell me this guys is CEL + trac + FLASHING VSC typical for these codes? I tried a zero-point-cal earlier to no effect. Within 30 seconds running VSC flash + trac on come up followed by CEL.

Hopefully a live stream is going to make things clear but that's about a week away and I'm impatient!


Thanks again!
'

BlackLexRX

I find both o2 sensors going at the same time odd too, that's what I said above. Not out of the realm of possibility though. I've had those lights before too, exactly like you're describing and it turned out my gas cap needed replaced. Bought a new cap at Napa (I know, OE, OE, but that Toyota cap failed once, so onto another) cleared my codes and they all MILs stayed off. I had different CELs than you described though, I think I had P0456 (evap system CEL). Maybe it's just your gas cap. That would also explain why there is no affect to performance. If you have another car handy, throw its gas cap on your RX, clear your codes and see if they go away.
Sounds crazy, but lots of people have had their gas cap go bad. Tons.

lexisaurus

While waiting for a chance to dive in a bit deeper and for parts to arrive I actually got symptoms. Reduced MPG, intermittent rough idle, intermittent loss of power/accel, minor vibration. I also got one instance of a P0352 which made no sense because that cylinder had a new coil-pack on it (dealership replaced this one instead of the correct one on cylinder 1 per P0351!)

Anyway I've been very lucky so far. I replaced B1S1 O2 which got rid of the CEL and O2 DTC. Still had a deceleration sensor zero undone so I did the zero calibration. Now no more DTCs or dash indicators. Citry driving seems back to 18-21MPG (it had dipped to 15 since I started this thread.)

Hopefully things stick and I won't get the coil-pack DTCs but won't be too surprised as they wouldn't come from nowhere?

Thanks for all the tips guys!

lexisaurus

Ahh spoke too soon but hoping this should be straightforward. I intermittently get A P0351 with appropriate symptoms = misfiring on cylinder 1. When I say intermittently I mean happening for 10 mins then all good for another 20 mins. The other odd thing is that there was a P0352 once the other day (and that cylinder has a new coilpack on it put on only weeks ago,) but other than that it's only been P0351.

Intermittent to me worries me more of a wiring/ecm issue than actual coilpack but I am not experienced... what do you guys think... just coilpack?


thanks!

350rx

I had recently got a check engine light with codes: P0172 and P0175. Engine light stayed on for a day and went away. Now the light has gone. I did replace my air filter a month ago with a KN air filter. Im thinking my MAF sensor is dirty?

lexisaurus

Interesting. Now that you mention this the P0172 and P0175 that I had did happen after oil change + filter as well and then they never came back.

The only recurring codes I've had are P0031 (kept recurring until O2 sensor was replaced the other day and hasn't recurred) and P0351 which as I'm saying seems very intermittent (drove another 2 hours in city today and it hasn't recurred.)