E49 code and possible solutions.
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HT4100 4.1, 4.5, 4.9 Discussion, E49 code and possible solutions. in Cadillac Engine Technical Discussion; Hello, I'm getting the E49 code in my 1990 Cadillac Deville with the 4.5. My vehicle is high miles somewhere ...
  1. #1
    Forgoten214's Avatar
    Forgoten214 is offline Cadillac Owners Enthusiast
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    Angry E49 code and possible solutions.

    Hello, I'm getting the E49 code in my 1990 Cadillac Deville with the 4.5. My vehicle is high miles somewhere around 260k.

    I am getting slight engine hesitation during acceleration I was told by the previous owner he only put cheap regular gas from no name stations in the vehicle while he owned it. I'm told by many people and the manual that you are supposed to use 91 Octane only in this engine. I assume this is one of the reasons why the vehicle has engine hesitation.

    I was thinking about "Seafoaming" my vehicle through the intake as well as gas system. Would this in anyway damage or help my vehicle? I know that in Northstar engines your not supposed to use Seafoam in the intake.

    Also will Gumout or Chevron cleaners help in anyway? What would your experiences be with your 4.5s or 4.9 vehicles using these solutions.

    Also, any other causes or reasons that could cause engine hesistation or the E49 code?

    Besides the engine hesitation and the vehicle running abit rough there isn't much other problems.

    Oh and I'm also getting about 12-14MPG average. Maybe a little less depending on where I'm driving. I assume this is attributed to the problems I stated earlier.

    Any help or comments would gladly be appreciated.

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    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: E49 code and possible solutions.

    I only run cheap regular gas from any old station and my 4.9 Deville has no complaints. I think E49 is an EGR problem. Your car should have EGR tubes below the throttle body that need to be cleaned out. You should check tha vacuum anyway to make sure everything is working normally.

  4. #3
    drewsdeville is offline Cadillac Owners Master
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    Re: E49 code and possible solutions.

    E49 is for a malfuctioning A.I.R system.

    Fresh air is pumped from the air pump to the diverter valve, which controls where the pumped air will go. There are 3 options:

    air cleaner
    cat converter
    exhaust manifold

    If the diverter valve is stuck or the diaphragms inside are leaking, this code will set. Considering the stumble and your mileage, I'm going to guess that yours is stuck or leaking to the exhaust manifold, corrupting the O2 sensor readings.

    Check diverter valve operation by pulling the hoses to each path listed above. At warm idle, air should be pumped to the cat converter, NOT to the exhaust manifold.

  5. #4
    daniel58 is offline Cadillac Owners Fanatic
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    Re: E49 code and possible solutions.

    I have had this code on and off for years on my 90 Deville 4.5. I have had lots of problems but it is running good now (except for the coastdown sail) with no stumble and its still setting the E49. Not to diss Drewsdevile's advice, he is usually spot on. But the AIR on the 90 diverts the air to the front exh manifold when the vehicle is cold then as it heats up switches it to the cat. So if I'm thinking right the O2 sensor will not see that air after the car is warmed up and should not be affected by the AIR code. But I could be wrong it seems to be a overly complicated setup easy to misunderstand. It certainly would be a good idea to check the ignition system out, make sure the O2 sensor is working, check for vacuum leaks and make sure you have the correct fuel pressure. I don't think those additives you mention will help, usually they are a waste of money and sometimes harmful. I also run regular gas with no problems.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: E49 code and possible solutions.

    Quote Originally Posted by Forgoten214 View Post
    I am getting slight engine hesitation during acceleration... I assume this is one of the reasons why the vehicle has engine hesitation....Besides the engine hesitation and the vehicle running abit rough there isn't much other problems...Oh and I'm also getting about 12-14MPG average.
    Two words....Vacuum Leak

    A vacuum leak will cause hesitation during acceleration, engine hesitation, engine running rough, crappy gas mileage, AND will sometimes throw an E49 depending on where the leak is.

    Look all over for cracked lines. Take a can of WD-40 and spray (lightly) the base of the throttle body, incoming lines, the A.I.R. system pump, the slew of vacuum lines that go through the firewall to run the A/C system, etc. If the engine rpm's change in the area you sprayed, you've found your leak...

  7. #6
    drewsdeville is offline Cadillac Owners Master
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    Re: E49 code and possible solutions.

    E49 sets when the PCM commands the diverter valve to/from the exhaust manifold, but sees 14 or less left bank block learn counts or less change. A vacuum leak cannot set an E49, unless the vacuum leak effects diverter valve operation (there IS a vacuum line to the diverter valve to pull the diaphragms). Since a generic vacuum leak has a global globally, rather than just the left bank, one will not set E49.

    As far as the diverter valve vs. the 02 sensor, Daniel, apply that description. As the engine warms up, air is routed to the exhaust manifold to aid in heating the 02 sensor. When the 02 sensor is ready and the system goes into closed loop, the pcm commands the diverter valve to switch to the cat. When the switch happens, the PCM watches how the O2 responds through the block learn. If the block learn does not change (decrease) by at least 15 counts, E49 will set.

    Therefore, if the diverter valve is stuck routing to the manifold, the PCM will not see any change in the block learn value when it tries to swtich the valve. Along with the set DTC, the O2 sensor readings on the front bank will be skewed lean, due to the high oxygen content from the fresh air pumped to the manifold. Of course, that bank isn't actually running lean, but the PCM doesn't know that. The incorrect A/F ratio on the left bank causes the stumble.

    Another way to verify if this is what is happening is to enter onboard diagnostics and view the LEFT block learn parameter. A high reading, anything far above 128, would indicate that the O2 sensor is reading lean and the PCM is dumping fuel trying to compensate.

    Else, a vacuum leak will show a global fuel trim change across both banks. Verify by making sure that the block learn values between banks are similar. If they are similar, you may have an issue seperate from the A.I.R. system problem, like a large vacuum leak.

    We should really post a sticky on the A.I.R. system operation and E49. It shows up here frequently and there's not much info about it. 99% of the time, E49 accompanied by a stumble or driveability issue is the above problem.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: E49 code and possible solutions.

    Quote Originally Posted by drewsdeville View Post
    E49 sets when the PCM commands the diverter valve to/from the exhaust manifold,...A vacuum leak cannot set an E49, unless the vacuum leak effects diverter valve operation (there IS a vacuum line to the diverter valve to pull the diaphragms).
    Exactly that's why I said what I said....It's fast to decipher (whether or not it is the problem) and is a free fix to boot. Beyond that, your technical advice is on par and far more encompassing as this is one (of a few) system(s) I haven't fully explored yet.

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    drewsdeville is offline Cadillac Owners Master
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    Re: E49 code and possible solutions.



    Not many of us regulars in the 4.X section anymore. All input is good input.

    Really though, we should think about organizing a few stickies for this section. There's not many of us here to answer and a lot of the same questions are repeated, this one included.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: E49 code and possible solutions.

    Quote Originally Posted by drewsdeville View Post
    Not many of us regulars in the 4.X section anymore.
    I find myself here because of the extensive work I've had to do...and because of it I've grown to love this motor...

    Quote Originally Posted by drewsdeville View Post
    Really though, we should think about organizing a few stickies for this section. There's not many of us here to answer and a lot of the same questions are repeated, this one included.
    Yeah, that makes sense...I've seen a lot of the same problems come down the pike here recently....

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    daniel58 is offline Cadillac Owners Fanatic
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    Re: E49 code and possible solutions.

    Oh yes it is a lovable motor, I particularly like changing the plugs repeatedly for some reason... but thats just me. And $500 for a new AIR diverter valve is so not going to happen. E49... its easily cleared. I have been thinking (dangerous) about drewsdeville's comments and I can see how the AIR could mess up the O2 sensor (only one on the 90 4.5) if it continuously diverted air to the front exhaust manifold. What can we do short of spending another $500 on a $700 car to fix it? I have read posts on here that say you can route the air pump output to the cat, but somehow with drewsdeville's comments in mind I think you would still get a code. How about removing the service eng light bulb? May not stop the codes but it would put that annoying light out of commission.

  12. #11
    drewsdeville is offline Cadillac Owners Master
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    Re: E49 code and possible solutions.

    Junkyard diverter valves are easy enough to get a hold of. Usually you can get them for no more than $10.

    First you'll want to make sure the check valves are working though. If the check valves are leaking, allowing hot exhaust to flow through the system backwards, that's what's burning up your diverter valve. You don't want the same thing happening to the replacement.

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    daniel58 is offline Cadillac Owners Fanatic
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    Re: E49 code and possible solutions.

    Those check valves have been replaced on my car, still getting E49. I know that dosn't mean anything because they came from NAPA (get the good stuff) and I did get a defective new Bosch O2 sensor from them.. I will check out the local yards, that is good advice. Been thinking about doing that anyway. Any idea as to what years are interchangable?

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    Re: E49 code and possible solutions.

    Cap everything and live with the light. Big deal. The code/CEL doesnt affect how the engine runs. Only the smog pump putting air into the manifold at the wrong time will cause a problem. People get so worked up about check engine lights.... As long as you know WHY the light is on and what action is taken by the computer as a result of it, you have little to worry about. In the case of E049 all you have to do is make sure your not getting air into the manifold to fool the o2 sensor.

    Forget everything I said if you live in a state where a CEL automatically fails an inspection....

    I've seen people drop hundreds of dollars simply to make a light go out. Its incredible. If they just arm themselves with a little knowledge they wouldnt be so scared of it. People are afraid of what they dont understand. Precisely why religion exists... Oops perhaps I've gone too far!

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: E49 code and possible solutions.

    Quote Originally Posted by Sevillian273 View Post
    Cap everything and live with the light...People get so worked up about check engine lights.... As long as you know WHY the light is on and what action is taken by the computer as a result of it, you have little to worry about.
    The problem with that is what if something ELSE throws a code, something that is more serious, you'll never know and let it go. My STS SES light is on because the CAT has/is failed/failing. Now I'm stuck checking my DIC every other day in case something serious is showing up....

    As a side note, where is the smog pump? When I rebuilt my 4.9 I didn't see one on there at all...

  16. #15
    Forgoten214's Avatar
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    Re: E49 code and possible solutions.

    Thanks for all the responses guys,

    as for the person that says forget about the light, if the light is on you wont be able to know if you get any new codes or problems because of the existing code that's already on unless you check the codes periodically.

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