1994 E420 Code4 and Code19
 

Hi,

I did the research on code 19 and know about the chip that Jim has. My questions is that I recently replaced the pipes going to and from the check valve on top of the air pump.

Could this cause me to get code 19?

Also when the check engine light came on I read the codes from the push button first and got code 4 and code 19. Then I read the codes at pin 4 got back a 1, pin 6 got back a 1, pin 7 got back a 6, and pin 19 got nothing.

Is this normal for pin 19? I thought I should have gotten something.

What causes code 6 at pin 7? I keep getting this code on that pin.

Is there an easier way to clear the codes on all the modules at once?

Thank you.

Code 6 on EA/CC/ISC is NSS switch contacts on that chassis.

You are not getting any codes on 19 b/c that is DM and DM will not report back any info until the car has done ALL emmissions self-test. That is N/59 Emmissions module and is the same as P/Button that you cleared the codes for CE with.

Code 19 coupled with 4 from DM would be b/c of vac leak from AIR system.

The answer to your code 19 and reset question comes with the use of a proper tool. Code 19 is an adaptation code so the obvious answer is to know what your adaptations are! Code 19 occurs when the adaptaions are used up. There are two separate forms of adaptations and the ones that are used up will tell the story. The chip doesn't change anything it just opens up a larger range of adaptation, so larger correctiona can be made by the controller.

A proper tool will clear all codes at once.

I reset all codes and checked the AIR system for leaks. The system is not leaking out of the pipes around the pump. I want to check the small vacuum lines but dont know how to.

Is there a good tool that I can buy?

After reseting the codes only code 19 keeps coming back. Code 4 no longer comes back.

4wheeling, checkout my main web page about halfway down for info on the 'dreaded' DTC#19 problem.

In any regard you can fix it cheaply. . . :)

The dreaded code 4 returned. I will check the fuel pressure and the vac lines and report back. Any chance the valve that is by the pump and the one by the washer fluid is bad? If so how do I diagnose them?

Thanks.

Here is what I have done so far to diagnose a code4:

I checked the fuel pressure regulator vacuum and it is 20 in Hg. There is no fuel leaking out of it. I still need to check the fuel pressure but I think it is ok as the car idles and runs fine.

I checked the vacuum source for the AIR pump it is 20 in Hg. I checked the vacuum input to each one of the vacuum change over valves and they are both at 20 in Hg. I then check the vacuum during a cold start to the diverter valve and it is also 20 in Hg. So up to know I dont have a vacuum issue. The only two things left are the diverter valve and the air injection check valve.

How can I figure out which one is faulty? What should I do next?

need more info..

Does the pump run?
If yes, when it does , does the SOV also open at the same time. ? ..these two questions are basically electrical concerns , as the clutch for the pump and the signal for the SOV require 12v supplied from the ECU.
so.. if yes to those 2 questions, you can then procede to air flow and the mechanical sections of the system....do you have vac coming out of the SOV to diverter valve actuating port?
If yes , then is that vac actuating the diverter to allow pump air passage? and is the check valve allowing that same air to continue on to the exhaust?
That is how the AIR system works and the code comes up when the 02 sensor does nor see or read the lean condition caused by the added air of the pump reaching the cat/exhaust for rapid cat warm-up...that is what the AIR system does and how it is monitored. A No Lean condition at 02 and the code pops #4. Which ONLY means the 02 self test performed by the Emmissions module has FAILED the test. What caused the sensor to not see/read a lean condition can be anything from a blown feed fuse on the supply end of the system [ electrical problem] , to a restriction/non operation at a valve [ mechanical/air flow problem] , to, finally, a possible weak/ bad sensor that is no longer capable to read the extreme lean condition of an otherwise working system .
In other words, do you have air originating from a pump and reaching the cat......yes/no/ and why ...that's it.
So, that is what you have to find out. It is between those two conditions somewhere and you can only find out by checking upstream/downstream from a common point ...and seperate the electical/mechanical sectors of the system. . It is a chain of components, both electical and mechanical, vac activated, that make up the system and you need to check its logic, step at a time, from the beginning to the end.

Thank you for your explanation. The last question I promise.:D What is the functionality of the air injection check valve?

Same as any check valve.....one way air flow.
You want exhaust going back up INTO the AIR System when it is not activated or the pressure from the exhaust is more than the pump???????????????????????????
Check valve eliminates that possible.....BUT, you could have a crapped up /stuck check valve that is not functioning ...and that will stop the air flow from the pump from ever reaching where it is supposed to go...
I think you get it. It is all about controlled air-flow at pre- warm-up.
Emmissions Device ..

Be aware that most AIR codes are caused by hose vac leaks or no pump engagement due to fuse, etc....but if those are found to be OK and one has a high milage 02 sensor, that is always suspect as a code 4 can actually be a technical tip-off of an aging/weak 02 sensor ,where the AIR system has in reality nothing wrong with it at all. That is where understanding the realtionships of codes and systems interactions are pragmatic....
In other words, a weak/old sensor that has become less sensitive and lost some range capacity is no longer capable of reading the very lean condition present with AIR system activation and will in effect report an inaccurate finding back to the DM with a perfectly operational AIR system..it is the monitoring 02 sensors sensitivity signal that is faulty, not the system. Kinda like a bad temp gauge telling you the car is running hotter than it actually is...so you go change the thermostat before checking the temp gauge and wind up with the same problem...so then you change the radiator ... nope, that didn't work, etc ....Diagnose Twice, fix it once....:)

Thanks again for your reply.

The pump does come on and runs for about 2 min on a cold start. The vacuum is also present on the line to the diverter valve. My next step is going to be to see if the diverter valve actually does what it suppose to and after that I will check the check valve.

The O2 sensor has about 40000 miles on it. What is the life expectancy of the O2 sensor? Thanks.

Bosch rates their O2 sensors for 60K miles . . . . most run them forever.

They can become contaminated by use of products that use "silicone". Read Menu#4a about a "MAF" that was contaminated. That will give you an idea what happens.

Something funny happened today. I was double checking the vacuum lines before I returned the rented gauge and the change over valve had no vacuum coming out of it. I think I found my problem. The valve is failing intermittently. I measured the vacuum twice before and it had 20 in Hg of vacuum coming out of it. All the measurements were during AIR pump operation to make sure the valve is energized. So I will replace the valve and report back. Thanks for all your help.

They get dirty and hang up..I squirt WD40 into the downstream line and let the vac suck it thru the valve. That clears them up. Same thing happens on the Purge Valves.

I found the source of the problem.:) One of the wires in the connector was never really soldered correctly and it was either touching or not. I re-soldered and tested the valve and it works now. I still did spray the wd-40 just in case.

I think this will solve the code 4 problem which I am hoping will solve the code 19 after I reset everything. Thank you all for your help and directions.

Well done.............

Good detective work . . .

Alas the DTC#19 code, if it's real, and I've never seen a 'false' one, will come back. the "book" says it can be caused by a vacuum leak or bad injector or two but I've never seen any of the other failures types.

Don't over-look this part

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2GN17VPXQ2GZ0RP5EF&yearid=1994%40%401994&ma keid=MB%40%40MB%40%40X&modelid=E%2D420%2D001%40%40E+420+Sedan&catid=C%40%40Fuel+Injection&mode=PA&su bcatid=C3000@@Fuel+Pressure+Regulator&source=www.peachparts.com&clientid=catalog.mercedesshop

It is a common failure part with age that will directly influence trims if it is leaking internally...the test is to take the vac line off and look for evidence of petro..there should be none. If there is, what happens is that raw gas gets sucked into the intake as UNMETERED fuel and the ECU can not correct w/o getting out of it's window frame %. So, code 19.

Takes 2 seconds to check and happens all the time. The best test is to run the car with the vac hose off for a few secs, as that will put the highest pressure on this part and if it is faulty, you will see fuel coming out the vac port.
Alway check that on fuel trims that have high adaptations/% and codes.

Thanks Arthur for the tip. I have checked the fuel pressure regulator as you mentioned. I pulled the vac line and let it idle for about 5 minutes and nothing came out. I turned off the engine and let it sit with the vac line off and still nothing.

This morning I cleared all the codes. It takes about 2 days for the CE light to come on. I will report back after 2 days or earlier if it comes on again. Thank you for all your help.

Very good..
Just thought I would mention that b/c I have seen it over-looked by so many
posters , only to later find that was the problem after they spent big $$$$ on everything else............
You prob just need to up the window % , but just don't want to do that if one just has a simple repair causing the adap to get out of line...........
The trick is ...is the adapt just basically normal for a used engine, or is the trim out of line b/c of a vac leak or a fuel pressure/injector, etc issue.
That chassis has a small % window, so it may well be it just needs some more leeway...that would be Jims upping the window % mod.
Later cars had a larger window to compenstae for more trims w/o a warning lamp or code, so that tells you something.
One other simple test I would do if the lamp comes back and related to FP is a FP test.
The FP is regulated by a diaphragm in that Regulator that is actualted by engine vac. So, a FP test consist of pressure with the vac line connected and with it disconnected. The higher reading is w/o vac line..the test is to see if the pressure DROPS in spec when the line is put back ON. If there is no difference , then the reg is bad and the excess to spec will cause the car to run rich, thereby bringing on a trim code .
So, look up the specs for your car on a FP chart. There will be 3 different specs to check:
1-FP w/o vac line attached [highest]
2- FP w/vac line attached [ lowest and working pressure].. this is the most important spec., as that is what the injectors see, and if too high, adaptations come into play.
3 - car OFF ---FP should HOLD for at least 30 MIN

These 3 test will tell all and are quite easy to do and should be done before any other test with your complaint.
If youy have a gauge and can not get the specs for that chassis , I will post them [ or archieves]

I have the a gauge so I will perform the test but I don't have access to the specs. If you could post them I would be grateful.

On a side note the CE light came back on yesterday afternoon on a cold start and only code 19 appeared. I will have to wait a couple days to see if code 4 comes back.

In the mean time I will perform the FP test.

Thanks.

LH/119 Fuel Pressure

Engine @ idle:

With vac ....3.2-3.6 Bar
W/O vac.....3.7-4.2 Bar

Engine Off for 30 min...No less than 2.5 bar

1 Bar=14.5 PSI

I have completed the FP test and here are the results.

Just ignition on and engine off and vac on I get 52 psi.
Engine on and vac on I get 46 psi.
Engine on and vac off I get 56 psi.
I let the car run with vac on for 30 seconds and shut the engine off. Right after I shut her off the FP falls to 40 psi and in about 20 seconds climbs to 52 psi.
After 30 minutes it is at 33 psi.

So looking at the spec everything is good except I don't know about the the values read after I shut her off.

Is that behavior normal?

Thanks.

Passed the test.............

So I assume the only remedy is the chip mod from Jim. Is there anything else I should check before I order the chip? Thanks.

Vac leaks...........including purge valve and egr.

I did check the vac lines for leak on both they are good. The change over valve for the egr I did not check as I don't know when it is activated.

When is the egr change over valve activated ie. when is there suppose to be vacuum down stream and vise versa?

I don't know anything about the purge valve. When it is suppose to be on or off or what ever it does. Any help with the above items will be appreciated. Thanks.

What I am saying is you can check hoses and stuff for vac leaks, but if a purge or egr valve leak, the leak is internal, so you do not see it..but the engine sure does,

So, they are hard to find and require a hand vac pump and gauge to really check. many times you can narrow it down by cappin each one and trying the car ..if the problem goes away, you may have found the culprit.
The real way is to get adaptation values and try and correct from there.

And again, with the small % window , the car may require that much adaptation and be normal. Even a bad/weak 02 sensor or clogged air filter can cause/require higher than normal adaptations in order to correct for the condition.
If you had the values and they were close, you probably need the extra % the mod would give you, but if the values are way high, the higher % mod is not going to solve the problem, but may just mask it.
A Fat guy can't climb thru a small window, but he can go thru a larger one...However, he is still too Fat .......:)
..and a normal guy can go thru the small window...
Not much of an anology, but you can see what I mean.
Does your car pop a code b/c of a fault , or is running and trimmed in as close to normal as possible, but just has too small an operating window %.
As said, the original was a borderline, small window that did not allow for a system that needed just a little more adaptation..that is where the mod comes in..[ and why Benz enlarged the window on later models] ..but don't think the mod changes the adaptations the car is requiring to run corrected..it does not..it simply does not trigger a CE at the higher adaptation % b/c the window is now larger and that means the CE does not pop b/c the adaptations are no longer higher than the new , larger window..ie, you got a bigger window now that allows for higher adaptation w/o CE warning...

That is a good question. I don't know how to read the values to see if I have a small window. All I have right now is a CE light which only returns code 19. How do I read the values? Thanks.

You don't see if you have a small window..you already know you do..that is what the modification does ..it give you a bigger window.., so the car can have a larger adaptation % without popping the CE and a code.

..but you need scanner equipment to get adaptation values...which is why we had you look for vac leaks and fuel pressure , etc ..hoping you would find something , as those few suggestions are common to effecting adaptation values. But you do not know those values and there is no way except with the equipment..
That is where it stands.

I just ordered the eprom from Jim. I will post back after install. Thank you all for your help.

Good. That will give you more % and as an engine and parts wear, the adaptations required go up anyway..so it is not a waste.

..and if you get a returning code, then you know you have a system failure for sure.

Ok, received your order and it's one the way . . .

Comes w/ a detailed instructions to install and the original MB TSB issued in '96. I always laugh when I read it b/c they waited until the car(s) was out-of-warranty before issuing the TSB.

Many cars have had the problem for model years '92 thru '94 so if you didn't report the problem, you were out-of-luck as far as having it fixed under warranty. Most didn't so they ponied up for a new module, around $2K!

BTW, I'm from "Rochester". . . my home town. Went to school and moved in '69 to So Cal.

I got the car from my father who bought it used at 89000 miles. The car had 122000 miles when I got it. As Jim would know, snow + rear wheel drive is not the best even with snow tires. So my father finally decided to get an SUV when she developed the ETA problem.

I needed a used car for my wife to learn how to drive on so I got a free car. Well almost free. I had to fix the ETA which was quite expensive. Currently 145000 miles and still counting. The engine and the tranny are strong. I hope to keep her until 200000 miles then see how she is holding up.

Thanks to this forum most of the repairs have been parts only otherwise she would have been junked long ago. The dealer here wanted $7000 to fix the ETA problem when $1800 (I decided to get a new one instead of a rebuilt one) fixed it. Thank you all.

You are entirely welcome . . . :)

I remember Rochester's winters. . . my 'stud' tires on my first new car, 1960 Bonneville. . . and how it used to eat the bottom/fender wells of all cars . . . :(

It has been 2 days since the eprom install and code 19 has NOT returned. I believe the problem is solved. Thanks to Jim and all of you who has helped.

Yes, and it won't return . . so just drive it and :) at those Rochester winters! :mad:

If you find (or acquire) a scanner such as the AST Retreiver (or equivalent), then you can read the S/A numbers directly and see how it's trending.

When mine tripped the limits at 0.85 (limits are +/- 15%), I replaced the eprom and it continued to trend downward. The new eprom has limits of +/- 32%, meaning it won't trip again until 0.68 is exceeded. That probably will never happen.

If I remember correctly it got to about 0.83 and I replaced the MAF and O2 sensor (b/c I got them almost new very little $$). The S/A was reset and after checking every month or two, the S/A was just on the "good" size reading 0.88. It has continued to rise to it's present value of 0.92 or so. And that's where it stayed.

Steve Brotherton (stevebfl) tried some experiments placing a 600 ohm resistor in the line which immediately changes the "precentage" and it raised the S/A to the "good" side of 0.85. He may comment if he read this.

But this is a nice fix and if you feel "rich" (or get a MAF and O2 cheaply), you might try replacing them. With new parts, it's a very expensive "fix" if it even works.

I am content with I have. No code so far and I am happy. Thank you all.