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I have a 2007 Lexus Rx400H. The CEL is on and throwing the following codes:
P0430- Catalyst System Efficiency Below Threshold Bank 2
P0172- System Too Rich Bank 1
P0175- System Too Rich Bank 2
P0101- Mass or Volume Air Flow Sensor "A" Circuit Range/Performance
After a lot of research I have learned this could be a number of things - air leak, O2 sensors, MAF, Fuel Pressure, Fuel Pump Etc. The car is jumpy at times, seems like the rpm is not consistent when accelerating. When the car is parked on an incline (with the fuel tank on a the down side) it has problems idling and will almost die. I checked two of the O2 sensors with my voltmeter, both showed resistance on the two black heater wires. The other O2 sensors are hard to get to.
Upon further inspection, I found a slight tear in this hose/boot (pictures below). What is this part called? Could this be causing my "Too Rich" condition?
Hi friend, I can't seem to find a diagram in my manual for hybrid air intake so hopefully someone knows if this tear is Before the MAF sensor or After the MAF sensor because it matters.
If torn before the MAF sensor there is no affect on engine live sensor data.
If torn after the MAF sensor the engine is gulping massive amounts of unmetered air and I believe the fuel trims will go positive and throw lean codes instead of rich codes like you have, someone correct me if I'm off on this.
PS- from your MAF code it seems you have a MAF failure or maybe harness/wire issue but not positive without more info so just a guess.
Hi friend, I can't seem to find a diagram in my manual for hybrid air intake so hopefully someone knows if this tear is Before the MAF sensor or After the MAF sensor because it matters.
If torn before the MAF sensor there is no affect on engine live sensor data.
If torn after the MAF sensor the engine is gulping massive amounts of unmetered air and I believe the fuel trims will go positive and throw lean codes instead of rich codes like you have, someone correct me if I'm off on this.
PS- from your MAF code it seems you have a MAF failure or maybe harness/wire issue but not positive without more info so just a guess.
I agree, after MAF would push system towards LEAN, not rich. Yes, there is a tear in the air cleaner hose, but you are getting rich codes. Fixing that tear will probably make the system go even more rich as you will further reduce air relative to fuel. Yes, that should be replaced, but you probably have another issue causing the rich codes.
Your MAF sensor is reporting more air than is actually being delivered. ECU then adds enough fuel to mix with the reduced air supplied and you get a rich condition detected at the O2 sensors.
I'd check the MAF connector, clean the MAF with MAF cleaner spray (not throttle cleaner!), and possibly replace the MAF sensor.
Could also be O2 sensors, but fix the cheaper/easier stuff first. MAF cleaner is cheap. Just be sure to spray the correct portion of the sensor and don't mechanically touch or brush the sensor.
@Seattle SCone - I have recently replaced and cleaned the MAF sensor with MAF cleaner.
I will probably go ahead and replace that hose, but not sure where to go next. The codes say O2 sensors Bank 1 and Bank 2 - arent there 4 O2 sensors? How would I know which ones to replace? Hopefully it would be the two on the under carriage - those were pretty easy to access.
I have a 2007 Lexus Rx400H. The CEL is on and throwing the following codes:
P0430- Catalyst System Efficiency Below Threshold Bank 2
P0172- System Too Rich Bank 1
P0175- System Too Rich Bank 2
P0101- Mass or Volume Air Flow Sensor "A" Circuit Range/Performance
If you have a scanner plz post live data including fuel trims.
Was any repairs done to the car before these codes came on?
Did they all come on at once?
Was the car driven regularly or has it been let sitting for an extended period of time?
Mileage?
Any more info you can add- strong fuel smell, shift points off, intermittent glitches, things not working, etc.
There are two oxygen sensors on each bank. The upstream sensors (before catalytic converter) are usually the ones that affects air / fuel mixture. The downstream sensor (post cat, aka #2 sensor of each bank) is used to measure catalytic converter effectiveness.
If you can get a graph of their voltages over a few minutes via OBD, that would be helpful in assessing the sensors' health.
If you have a scanner plz post live data including fuel trims.
Was any repairs done to the car before these codes came on?
Did they all come on at once?
Was the car driven regularly or has it been let sitting for an extended period of time?
Mileage?
Any more info you can add- strong fuel smell, shift points off, intermittent glitches, things not working, etc.
@Margate330 there have been no repairs. They have all been on for quite some time with no noticeable symptoms except occasional shudder of engine (especially parked on incline). No smell of gas.
i am not sure if this is helpful but I hooked up my BlueDriver and did the live scan while the car idled (engine on the whole time). The first picture is where it stayed the majority of the time. Second picture is when o2 sensor spiked up- but nothing changed in the rpm, still just idling.
There are two oxygen sensors on each bank. The upstream sensors (before catalytic converter) are usually the ones that affects air / fuel mixture. The downstream sensor (post cat, aka #2 sensor of each bank) is used to measure catalytic converter effectiveness.
If you can get a graph of their voltages over a few minutes via OBD, that would be helpful in assessing the sensors' health.
Bank 1: 25% LFTF + 7.8% STFT = 32.8% total fuel added
Bank 2: 27.3% LFTF + 8.6% STFT = 35.9% total fuel added
Yeah looks like you have a pretty serious vacuum leak. lol
As far as the MAF I find it easiest to check at idle with the car warmed up but most scanners output MAF in Ft/min which doesn't offer the resolution in my opinion to judge bad from good like measuring in gm/sec. At idle with car warmed up MAF should be around 0.4ft/min and idle around 700 rpm. When revved up to 1,000 rpm I get 0.7-0.8ft/min.
Here is some of my live data for comparison.
Revved up to 1,000 rpm my MAF bounces between 0.7-0.8.
Bank 1: 25% LFTF + 7.8% STFT = 32.8% total fuel added
Bank 2: 27.3% LFTF + 8.6% STFT = 35.9% total fuel added
Yeah looks like you have a pretty serious vacuum leak. lol......
Oh. Heavens. I didn't notice those LTFT's are POSITIVE, not NEGATIVE. The ECU is indeed compensating for a LEAN condition, not a rich condition as reported in the trouble codes. The lean condition is also about equal on both banks. So, it is extra air, not detected by the MAF, being delivered to both banks.
Your tear in the intake ducting, post MAF, will cause exactly the lean condition seen on your LTFT's. Replacing that or temporarily taping up the tear should go a long ways towards reducing vacuum leak.
With regards to sensor #1 values, what I was wanting to verify is that they swing up and down over a range of at least 0.6 to 0.2 volts.
Last edited by Seattle SCone; 03-04-21 at 09:38 PM.
I believe that yes a tear in the that air box hose like some of the others eluded to will cause the cel as well as codes to pop so its probably best to replace the entire hose rather than try and tape up the hose.
I must say, that hose was WAY more torn than originally thought. Very surprised it ran as good as it did with this much of a tear:
Got the part from the local Toyota dealer and installed on Saturday. It runs soooo much better! All the Oxygen sensor / MAF codes have disappeared. The only code left is P0430 - Catalyst System Efficiency Below Threshold Bank 2. So I guess my quest for no check engine light continues on to that code. Cant thank this community enough!
03-03-21, 03:22 PM
RX400H - P0172 & P0175 - System Too Rich
