Intermittent Check Engine Light

[Maui Blue]

Well, I got the harmonic balancer problem sorted out. Onto the next...

 

I am having an issue with the  Service Engine Soon light.  It comes and goes intermittently.  I performed the dashboard check but all the codes were followed by the H (indicating a history problem that has been cleared).  There were a few codes but they are difficult to interpret since some of the LED segments are confusing. Some are off, some are dim and some are bright. No idea what that means.  

 

One of the history codes is E041H.  It is interesting to note that the check engine light also flashes the 41 code like some other GM cars but I found no mention of it anywhere here. Should I assume the 041H indicates an old issue.  If so, what does the Service Engine Soon light flashing 41 tell me?  

 

041 seems to be a common problem with the cam sensor magnet but from my reading it should be a constant light, not intermittent.  Would that indicate some problem other than the cam sensor magnet?

 

I'm overdue for California  smog check.  Now that it is running right (after the harmonic balancer replacement) I need to jump on this next. All assistance very much appreciated.

 

Thanks

[Maui Blue]

I guess I included too much detail in the original post...

 

Can anyone explain the Service Engine Soon light flashing code 41 and what it might indicate? 

 

Also,  I took the car to O'Rielly's Auto Parts store.  They performed a free check using an OBD1 code reader.  It returned a code of  P0446.

 

As I understand it that could point to several different issues.  Does anyone have any experience with this code and what the most likely problems might be?

 

Thanks.

[DAVES89]

Please post the year of your Reatta on your signature line so we can tell what year what car we are helping you with. The Reatta looks the same through all 4 years but is not the same car.

[Maui Blue]

Dang it!  I completely forgot to specify.  I will add it to the signature line, but for now it is a 1990.

[Ronnie]

On 11/4/2018 at 8:38 PM, Maui Blue said:

041 seems to be a common problem with the cam sensor magnet but from my reading it should be a constant light, not intermittent.  Would that indicate some problem other than the cam sensor magnet?

 

Possibly a bad cam position sensor or a bad connection in the wiring going to it. However, the cam interrupter magnet in the timing gear doesn't always just fall out all at once. It can come apart a little at a time because the magnet is actually 4 magnetic rods combined into one housing.  They can break into pieces or fall out individually. That might account for your intermittent code E041 in history. Best way to tell if that is the problem is to remove the cam position sensor and take a look. Padgett has written a good tutorial on replacing the cam magnet. It is here.

 

On 11/6/2018 at 4:01 PM, Maui Blue said:

Also,  I took the car to O'Rielly's Auto Parts store.  They performed a free check using an OBD1 code reader.  It returned a code of  P0446.

 

As I understand it that could point to several different issues.  Does anyone have any experience with this code and what the most likely problems might be?

 

The other code you are getting (PO446) is likely to actually be a BCM code B446 which is a low AC Freon code. There are no 446 ECM codes.

 

It would be wise to use the onboard diagnostics instead of shorting the ALDL pins and reading the flashes. It is a great diagnostic tool once you learn how to use it properly and understand what it is telling you.

 

 

[Maui Blue]

I replaced the gas cap today hoping for a cheap fix.  No luck as the Service Engine Soon light just came on again.

 

It was still on when I turned off the engine (it's intermittent) so I thought this would be a good time to run codes again.  There are NO current codes!  Just history codes.  Very frustrating. 

 

It is possible that the P0446 code is for low Freon as suggested. I had been thinking about topping it off since the cooling efficiency seemed to be lacking recently. According to the reference material this does not set the SES light so the problem must be elsewhere.

 

The interesting thing about the SES light flashing 41 is that I had NOT shorted the ALDL pins and the connector cover is in place.  I was running the on-board diags as described and noted the flashing.  It flashes 12 three times then the 41 code 3 times and then repeats 12 three times, which is familiar since I have used the paperclip method and counted flashes in other older GM cars.   It does this repetitively as long as I am in the diag mode.

 

 

Edited November 8, 2018 by Maui Blue (see edit history)

[2seater]

It is normal for the SES light to flash while in diagnostics but to be honest, I never paid any attention to the rate or code hidden in the flashes? I don't believe there is any reference to observing the SES light while in diagnostics in the FSM? My car is put away but I may take a look at that.

[jonlabree]

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction. The code P0446 is set when the engine computer recognizes a fault or restriction at the vent control part of the Evaporative emission control system (EVAP).

[Maui Blue]

16 hours ago, Ronnie said:

 

Possibly a bad cam position sensor or a bad connection in the wiring going to it. However, the cam interrupter magnet in the timing gear doesn't always just fall out all at once. It can come apart a little at a time because the magnet is actually 4 magnetic rods combined into one housing.  They can break into pieces or fall out individually. That might account for your intermittent code E041 in history. Best way to tell if that is the problem is to remove the cam position sensor and take a look. Padgett has written a good tutorial on replacing the cam magnet. It is here.

 

 

The other code you are getting (PO446) is likely to actually be a BCM code B446 which is a low AC Freon code. There are no 446 ECM codes.

 

It would be wise to use the onboard diagnostics instead of shorting the ALDL pins and reading the flashes. It is a great diagnostic tool once you learn how to use it properly and understand what it is telling you.

 

 

 

Well, I finally got the E041c code. Previously it had only appeared as a history code.  It was out of shear frustration that while sitting in the car getting ready to go home I entered the diagnostics with the engine running. Nowhere is there any documentation in the manual or on the web that I have ever seen that states anything other than putting it in the "ON" position.   What a waste of time!  The code showed up immediately with no other codes reported.  But it does seem to confirm that the flashing 41 code was correct in that the current code is indeed 041.  (The P0446 code was pulled using an OBD1 scanner by O'Rielly's Auto Parts)

 

So now the process begins...  I will start by inspecting the wires, connector and sensor.  Hopefully that will identify the problem.  If not, I am curious about the magnet procedure. It seems straightforward but I do have a question.  How does one bring the magnet into view through the hole?  I have no idea how to turn the engine or to identify the Top Dead Center position.

Edited November 8, 2018 by Maui Blue (see edit history)

[Ronnie]

1 hour ago, Maui Blue said:

How does one bring the magnet into view through the hole?  I have no idea how to turn the engine or to identify the Top Dead Center position.

 

Remove the cam sensor so you can see through the hole it covers. Put a large socket on the bolt that holds the harmonic balance onto the crankshaft. Turn in a clockwise direction until you see the cam magnet as shown in Padgett's instructions. You may have to turn the crankshaft more than you expect because the camshaft turns at half the speed of the crankshaft. I don't know why you would need to identify top dead center.

[Ronnie]

2 hours ago, 63viking said:

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction. The code P0446 is set when the engine computer recognizes a fault or restriction at the vent control part of the Evaporative emission control system (EVAP).

 

 P0446=OBDII code

[jonlabree]

Also OBD 1

[Ronnie]

6 hours ago, 2seater said:

It is normal for the SES light to flash while in diagnostics but to be honest, I never paid any attention to the rate or code hidden in the flashes? I don't believe there is any reference to observing the SES light while in diagnostics in the FSM? My car is put away but I may take a look at that.

 

I had never paid any attention to the flashing SES either until he mentioned it.  I just checked and it does work for the ECM codes but I couldn't see how to read BCM codes with the flashes. It would be a handy tool on the later model cars where you access diagnostics with buttons, but on early models with the CRT it would have less value unless there is a way that I don't know about to access the diagnostics without the CRT or the paperclip method.

[Ronnie]

11 minutes ago, 63viking said:

Also OBD 1

 

You should contact GMTuners.com and let them know. They left the P0446 out of their OBD 1 code list.

[Ronnie]

Jon, After thinking about how my last post sounds, I apologize that it came out that way.  You may be correct in what you said. I was just saying that I can't find that ODB-1 code anywhere and Sinister, who probably programed your chip for your supercharger, doesn't have it listed.

[2seater]

1 hour ago, Ronnie said:

 

I had never paid any attention to the flashing SES either until he mentioned it.  I just checked and it does work for the ECM codes but I couldn't see how to read BCM codes with the flashes. It would be a handy tool on the later model cars where you access diagnostics with buttons, but on early models with the CRT it would have less value unless there is a way that I don't know about to access the diagnostics without the CRT or the paperclip method.

Very interesting although I am not sure I see the value of it, no matter the year? It seems much easier to read the code directly rather than interpreting a flashing light. I suspect it is a leftover from when the only code reading available was by shorting the ALDL? I agree the "P" code sounds like OBD II, and while I have no way to prove it now, I have a vague memory of my old Auto X-Ray scanner displaying codes like that. I didn't really use it to read codes on the Reatta, but I did use it to record ALDL data during my early tuning efforts with the turbocharger, so I may have that confused with later OBD II vehicles I have.

[Ronnie]

I was thinking it might be handy on the later models If the IPC was out. For diagnosing problems you can't beat the CRT.

[Maui Blue]

Here is what I hope is the last update to this issue.

 

Based on all the best evidence and advice I purchased both the cam position sensor and the interrupter magnet. I removed the sensor (after removing the water pump pulley) and examined the interrupter magnet. (Incredibly, it was viewable through the hole without rotation. What are the odds!)  The magnet looked a bit dirty but seemed to be intact. I replaced the position sensor with the new one and crossed my fingers.  No luck.  The check engine light returned almost immediately. Since I was certain that my problem was one of the two items I purchased I decided to have a closer look at the magnet.  I did the disassembly again and had to rotate the crankshaft a bit to find it. Not as difficult as I thought it might be. I did some cleaning of the interrupter to make sure the magnet really was still inside the plastic cap since my initial inspection was done by reflecting a flashlight beam off the inspection mirror I was using.  It all looked to be in excellent condition so I reassembled and regrouped. (I reused the original sensor since the connector locking stub snapped off when I disassembled it.  Bummer!)

 

I was lost for what else to do so I started semi-randomly checking things under the hood. I checked again for any cracked or broken hoses and various connectors.  I pulled the coil pack from the ICM and noted that one of the connectors seemed a bit loose.  I may have pulled it loose while separating them?  I crimped all the connections a bit and reassembled. 

 

From there I decided to inspect the IAC (Idle Air Control) valve. I've done this on other 80's era GM cars and thought it probably needed cleaning anyway.  When I removed it I found that it was very dirty and caked with residue as was the orifice in the throttle body. I doubt that it had ever been replaced in it's 130K mile life.  I didn't have a replacement as I was doing the repair at a friends house out in the boonies on Sunday (Veteran's Day). I used spray throttle body cleaner, and some light scraping on the IAC cone, to do the cleaning. See before and after pics below.  As a side note, I wore a paper filter mask while doing all this due to the very high particulate count (smoke) in the air due to the tragic Camp Fire that leveled Paradise, CA which is a few hours away by car. 

 

After completing the items above I decided to give it a test drive to check it out. I had no confidence that anything would change since I didn't really do anything that seemed related to the issue according to the error code and the research I had had done.  I was surprised to find that the light did not return. Since then I have driven the car about 2 hours with no recurrence. At this point I am cautiously optimistic.  So whether it was the coil to ICM connections, or the dirty IAC / orifice, I have no idea. But I am recording it here in case it might help others with the same problem.  

Edited November 14, 2018 by Maui Blue
fixed typo (see edit history)