P0093 Help Needed To Decipher Data

Badger1966 · February 20, 2016

You will never believe it. I did a diagnostics on it earlier. P0093 again. They have done the fuel filter and also concluded there were no fuel leaks or low fuel pressure. How on earth can I still have a p0093 fault? Crazy.

Shahpor · February 20, 2016

This is very strange.

I know it is probably of no help, but this is what the manual says about fault code P0093

I would assume the Lexus guys would have run through these tests though, so this is probably redundant.

Very curious to know what exactly is wrong with the car.

mackemade · February 21, 2016

Hi Badger,

i have a similar problem with my lexus 220d, it will start on a morning and run fine for about 200 yards then cut out , VSC, TRC, and EML will come on. it goes into limp mode. when i put my code reader on it it shows p0093 major fuel leak. if i clear the code the car will run ok all day, until it is left over night then we have to go through the same process.

is this the same for you ?

i am stumped on what is going on with it.

thanks

mackemade

Badger1966 · February 21, 2016

Very interesting reading Shahpor, I guess they did do all that, but I wasn't with the mechanic at the time. But they did report absolutely no leaks which is why the fuel filter was changed because it had low fuel pressure. Filter changed and fuel pressure good.

And Mackemade, yes, your problem is exactly the same as my problem. But mine goes into limp mode numerous times from about 10 seconds after I start to approx half a mile, The hotter the engine gets, the less it does it until it runs ok, Could be 2 times up to 8 times. Although I don't have a handheld tester so I just repeatedly turn the car off and back on until it keeps running. I find that the colder the morning the worse it is. Very strange. But since I had the Air Fuel Sensor changed the problem has got a little worse. Although since the fuel filter and sensor change, the car runs much better when it runs.

I'm going to try and hook up the diagnostics again later today. I did have another fault code yesterday but I can't remember what it was. Catch up with you all again later.

Out of interest Mackemade, what mileage does your 220d have, and what sort of mpg do you get?

mackemade · February 21, 2016

hi badger

it has 119k on the clock and will average about 32mpg some town some motorway driving but it has got progressively worse it used to do 38mpg.

i have to clean out the erg every 5k, but i dont know if this is related,

i have had the fuel filter changed this week, but made no difference, i was told that there may be a small leak from one of the unions, and as the car is left the pressure drops.

when the car is started it sucks in some air and when this reaches the injectors then it will cut out.

what do you think, does yours cut out, mine will go into limp mode then stall..

Badger1966 · February 21, 2016

Hi Mackemade, yes, mine will not rev above 1500 ish rpm and after a short while it will stall. And you have an interesting theory. Although the code states large fuel leak. Also I have absolutely no sign of any fuel leak. I would imagine if the system remains pressurised after the engine stops, you would at least see some sign of diesel somewhere, or even smell diesel. Also for air to get into the system you would need a vacuum to suck the air in, or a large enough hole for air to naturally get in. Either I would have thought would show some sign of diesel leaking. Also I never have to prime the system to bleed any air out before starting again. This is all me just guessing though!

It is very strange how the car will run once it gets its act together. Also we are both suffering from mpg going down. I think there can only be two reasons. A leak, or more fuel being injected.

Any way, Just ran diagnostics. I had 2 fault code show up. I then saved the time stamp data. Went back in to look at it and it showed 3 fault codes? B2283 being the 3rd. Crazy car..

Codes are...

P0093 Fuel leak large

C1201 Engine control system malfunction

B2283 Vehicle speed sensor

I don't know how related all this is. But after new MAF, Fuel Filter and Air Fuel Sensor, I still have exactly the same problem, I dont know whats next.

Fingers crossed the next visit to Lexus will sort it!

mackemade · February 21, 2016

hi

mine is in the garage now, hopefully getting somewhere closer to solving the problem, ( they have had it a week already),i will keep in touch, let me know how you get on. surely someone must get a solution eventually

will never buy another lexus diesel, never heard of anyone not having a problem

Badger1966 · February 21, 2016

Good luck Mackemade, my fingers are crossed for you! And yes, please keep in touch. Strangely though, I've just come back from visiting my parents. Half way there, the faults have reset, I looked at the dash and no lights on. And on the journey back, all ok. Car going really really well. The car is crazy. Out of interest, is it a Lexus main dealer garage?

mackemade · February 21, 2016

its an independent

like i said i can get the lights to clear, but it comes back when it has been left over night, see what yours is like in the morning. that is when i have the problem

Badger1966 · February 21, 2016

Indeed, if I was a betting man, I would would certainly bet on them coming back in the morning, lol. I will let you know.

Badger1966 · February 22, 2016

Yep, must have gone into limp mode 10 times on the way to work.

mackemade · February 22, 2016

just a thought, mine developed this after i forced regenerated the DPF , wonder if that is linked ?

mackemade · February 22, 2016

ps, how far did it go before it did it the first time this morning and did it cut out

thanks

Badger1966 · February 22, 2016

Well these days I tend to stay stationary until it gets it act together. But usually it starts within 30 to 60 seconds and can go on for 5, 10 sometimes 15 mins before it will run. If I do just start and drive, I am lucky to get 200 yards before it goes into limp. Don't even reach the end of my not very long road sometimes. And yes, it cuts out every time. The hotter the engine gets, the less it happens, until it runs ok. So I guess heat is an issue which is why it always happens from cold. I guess things that are affected by heat are engine, coolant, and exhaust. And remember, mine often smokes a lot before it gets up to full operating temperature if I have the heat on in the car.Turn the heat off and no smoke. How mad is that. Although it hasn't done that for a while now. But it did do it this morning. And another crazy thing is that the outside temperature needs to be below approx 10 degrees for the smoking thing to happen. It is all very crazy indeed. I like to think I am quite good with vehicles. I can strip an engine and rebuild etc. And good at fault finding problems, but this car is nuts! In all my life I have never experienced such weirdness in any vehicle!

I'm not sure how regeneration is linked to a P0093 code. Regeneration of the DPF is exhaust, not fuel. Although I think the 5th injector is used some how for regeneration, but not sure. And my diagnostics say my DPF is fine, and Lexus confirm it is fine as well. Not to mention that Lexus couldn't find anything wrong, even after an hour and a half live test. Other than the air fuel sensor. So I have no idea what they are going to find next week. If it does turn out to be the DPF, the cost would write the car off. I think I would consider getting the DPF gutted, block the 5th injector, fit an emulator and have a re map done. Needless to say, the car is getting worse. Next week will be very interesting indeed!

Cheers.

Badger1966 · February 23, 2016

This morning I thought I would start it and go. Didn't get 20 meters. Restart, then about 200 meters, restart, then about another 200. Restart and just make it to work, 0.8 mile from home. Left it ticking over for 5 mins. Then started 25 mile journey to head office. Didn't miss a beat. Outside temp, 3 degrees. Put heater on and no smoke today. Arrived with average of 25.5mpg.

Shahpor · February 23, 2016

So it only happens when it is cold?

Did Lexus check the coolant sensor?

Also, when it is cold and the switch on the air con, does the idle rise to 1200rpm?

Badger1966 · February 23, 2016

Hi, yes, only in the morning when cold. Or any time during the day if is has been left to get cold. But always goes into limp mode more often first start of the day.When I turn on the heat, air con or not, the revs automatically rise. No idea if Lexus checked the coolant sensor. But it didn't show as faulty on diagnostics.

Cheers

Shahpor · February 23, 2016

I agree that it should throw up an error, but at this point I am clutching at straws.

If you are handy with a multi meter, you can always test the resistance.

Badger1966 · February 23, 2016

Top man, thanks. I am handy with a multimeter, so I will give it a go. Cheers.

is200 Newbie · February 23, 2016

Maybe a stab in the dark and I know nothing about diesels ..... wont cost anything but check the seal on the fuel cap or the caps on secure. The petrols create a vacuum and there has been a few reports of spurious goings on linked to unsecure petrol caps.

Its a reported problem on some Vauxhalls where the rubber seal fails causing issues.

Badger1966 · February 23, 2016

Hi, I have considered that possibility, but the system shows correct fuel pressure since I had the fuel filter done. Also I would imagine I would get problems all the time and not just until the engine starts to warm up. Unless the pressure builds up and then creates a seal. Having said that, nothing would surprise me! Unfortunately if Lexus cant find the problem next week, I am literally at the point of replacing parts until I cure the fault. Grim. I would like to think that lexus would not like the world to know that they can't fix one of there cars though!, lol

Any way, my journey back from head office, 25 miles. Outside temp 11 degrees. Started car, within 30 seconds into limp mode. Started again drove away and got around 200 meters until limp mode again. Started car and no problems again. Averaged 26.5 mpg. So, higher outside temp, less going into limp mode and slightly higher mpg than this morning.

I did another little test on my journey. 1st, 2nd, 3rd gear. flat road holding the throttle steady between 2000rpm and 2500rpm. Engine power was pulsing for want of better words. revs rising and falling very slightly and very rhythmically. You can also hear it. I could also feel it, as in I could feel my body moving forward and backwards sometimes. I can't help but think it can't get the fueling right. Which also makes me think thats the reason for the poor fuel economy, it's seriously over fueling, running very rich. And to that end, could that be the reason why I get the P0093 fault? Combined fuel consumption should be around 44mpg? Even if I was getting 30 mpg, that's, I think 37% less than it should be. Could that be enough extra fuel usage to make the ECU think the car has a fuel leak???

mackemade · February 26, 2016

hi badger,

just had the garage on the phone, after a week they have discovered that the fuel pressure sensor has an intermittent fault. most of the time it is fine but then it will not function correcllt and then return to normal. it is going to be changed so lets see

will keep you update, any news your end?

Badger1966 · February 26, 2016

Well thats great news indeed! Mine is going into lexus on Monday. I will mention that to them. I feel sure its a fueling problem so fingers crossed. As for mine, its still the same old thing. As soon as I know anything I will let you know.

mackemade · February 28, 2016

i am not convinced its that

Badger1966 · February 28, 2016

Lol, I know what you mean. But if it's faulty, replace it anyway. Hope it doesn't cost as much as my air fuel sensor did! Which didn't fix the fault. Well mine is in to Lexus tomorrow for as long as it takes to fix. Lets see what they come up with.

Out of interest, I just read this..

The Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which resistance changes with pressure. The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signal to the Powertrain Control Module (PCM) corresponding to pressure.

Strain gauge type sensors are consider passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow.

Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The FRP sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each combustion cylinder.

This could be the fault, if the highlighted bit above is correct, maybe this could explain the low fuel consumption. Too much fuel being injected?