Cruise Control not working & check engine is one

[Kris G]

Hey everyone,

 I have a automatic transmission 2005 Subaru Impreza Outback sport that I just got and it has a few issues. I can't tell if they are linked or not, I am not really a car guy myself, or if they are all different things that just need to be repaired. My cruise control light is blinking with my check engine light. I went to autozone to run my codes and the only one that came up is the P0420 which is related to my cat which surprised me a figured that the cruise control or something from the engine would've come up. I do think one of my stablizer bars/axles are unstable becuase my steering wheel is kinda shaking abnormally and my power steering is weird which could be the check engine, but nothing comes in line with the cruise control disabled. Does anyone have any thoughts or fixes, im in the dark myself, anything helps. Thanks.

Edited May 18, 2022 by Kris G
Rewording

[Numbchux]

Cruise control is disabled whenever the check engine light is on, in those cars.

Pretty long and well-documented diagnostic process to the P0420.

[jonathan909]

Again, by coincidence, this just popped up on the '06 OBW I recently did the head gaskets on.  I didn't know this is A Thing.

Would you please be so kind as to direct me to the best summary on the problem/solution?

[idosubaru]

1 hour ago, Kris G said:

Hey everyone,

 I have a automatic transmission 2005 Subaru Impreza Outback sport that I just got and it has a few issues. I can't tell if they are linked or not, I am not really a car guy myself, or if they are all different things that just need to be repaired. My cruise control light is blinking with my check engine light. I went to autozone to run my codes and the only one that came up is the P0420 which is related to my cat which surprised me a figured that the cruise control or something from the engine would've come up. I do think one of my stablizer bars/axles are unstable becuase my steering wheel is kinda shaking abnormally and my power steering is weird which could be the check engine, but nothing comes in line with the cruise control disabled. Does anyone have any thoughts or fixes, im in the dark myself, anything helps. Thanks.

 

It's totally normal for the cruise control to turn off when the check engine light comes on - yes it's dumb but that's what they do. 

"Shaking abnormally and power steering" - are not related to the check engine lights.  Start another thread asking about those and give better details.  Take note: Neither of those is a big deal - meaning they aren't going to leave you stranded (very unlikely anyway, I am making some assumptions with limited info).  Very briefly:
a. shaking during braking (like exiting a highway) is just a front rotor that's warped. Very common and benign but annoying.  Have the front rotor(s) turned if you can find a place to do it. Shop across the street from my office does it for $15 if I take them the rotor.  You absolutely don't need new rotors and if your current ones are stock they'll be higher quality metal and less prone to rust than generic replacements.

Power steering - 05-09 power steering systems in Subarus have issues.  Describe your specific symptoms and start annother thread. 

P0420: 
1. If you have any exhaust leaks - fix them first. 
2. General tune up - ideally you get new NGK spark plugs, Subaru or NGK spark plug wires, new PVC and see if you get lucky and the code goes away. 

Usually it doesn't. 

You're better off ignoring the P0420, check engine light, and just get used to not having cruise control.  You can drive 100,000 miles all day long with a P0420 code. It's All but meaningless on a nearly 20 year old vehicle.  Unless you're getting horrible gas mileage but you didn't say that. You can sometimes diagnose it and end up with a simpler solution - but you're highly unlikely to find the technical expertise to do this so usually it's just simpler to install a new converter.  99% of shops are just going to install a new converter.

If you need it fixed you'll need a new catalytic converter and preferrably a Subaru one as aftermarkets are prone to early failure. If you get aftermarket which might be your only reasonble choice get a Wagner or other well known brand. 

[brus brother]

05 OB had P0420 at 105K until I junked the car with 200K miles. Tried replacing the cat (aftermarket) without change except more change out of my pocket.

Computer is tuned real tight for emissions. It may clear itself but will come back. I bought a $20 code reader/eraser so I could pass our testing every two years.

Clear code, ru at a partiocular sequence to set system checks as ready then run to get emissions test good for 2 more years. I think I did that for the last 8-10 years of ownership. 

Put a piece of black tape over the light Costs nothing.

If recent purchase, prior owner probably knew the tricks.

[idosubaru]

18 minutes ago, brus brother said:

05 OB had P0420 at 105K until I junked the car with 200K miles. Tried replacing the cat (aftermarket) without change except more change out of my pocket.

Computer is tuned real tight for emissions. It may clear itself but will come back. I bought a $20 code reader/eraser so I could pass our testing every two years.

Clear code, ru at a partiocular sequence to set system checks as ready then run to get emissions test good for 2 more years. I think I did that for the last 8-10 years of ownership. 

Put a piece of black tape over the light Costs nothing.

If recent purchase, prior owner probably knew the tricks.

 

This - that experience is very common, and not rare.  Take his advice seriously, it's not anecdotal. 

[jonathan909]

If that's correct, and the tolerances are too tight, I can see that all the expensive replacements in the world won't fix it.  But the tape-over-the-CEL thing isn't happening.  That worked for the Velvet Underground, but otherwise it sounds like pretty bad advice, as that way you don't see the blinks when additional codes are thrown.  And we don't have to do (periodic) emissions testing around here, so that's not a consideration, but being able to use one's cruise control - as well as getting decent mileage - is.

So I'd like informed opinions on the various fixes appearing around the 'net, because for the most part they appear to be on the edge of bogus.  For example:

Cleaning out your cat with soapy water.

A can of commercial cat cleaner in the gas tank.

Putting a spacer between the O2 sensor and the cat.

etc.

 

Edited May 20, 2022 by jonathan909

[1 Lucky Texan]

On 5/18/2022 at 1:12 PM, jonathan909 said:

Again, by coincidence, this just popped up on the '06 OBW I recently did the head gaskets on.  I didn't know this is A Thing.

Would you please be so kind as to direct me to the best summary on the problem/solution?

not a summary, but quite detailed; http://www.subaruoutback.org/forums/66-problems-maintenance/49537-p0420-diagnosis.html

[ccrinc]

I have a 2009 Forester. EVERY time it is driven under a load (like going up hill, over 42-4500rpm for over 2 minutes), this condition manifests itself. EVERY time. Cruise light flashing and cruise disabled, check engine light on, traction control light on (if  you have that).
When I put my scanner on it, it always comes up with the PO420 code. Always. But the car runs fine. Both O2 sensors have been checked, cat's ok, no other issues. I have come to the conclusion that there is something about that that thinks the car is being overstressed so I simply don't drive it like that. (My grandson, however,...)

So, I clear the code and go on my way. And it will run fine for months, or until grandson drives it again.

[1 Lucky Texan]

any exhaust system damage?

you may need to look at live data from the ECU

[brus brother]

P0420 for 8 years gas mileage never altered (even with the black tape). Car ran great all those years. There was another trick of installing a resistor on one of the O2 sensor wires and while the P0420 disappeared, another code popped up instead.

If you end up not getting a resolution, you can erase the code with a $20 reader and cruise will work until the code reappears. You can also just read codes on a routine basis and allay concerns if you fear a code warning that the rear tires are about to fall off. I think that code is Pwtf!

Seriously, I wish you luck. Hope you can report good news.

[idosubaru]

On 5/20/2022 at 5:48 PM, jonathan909 said:

If that's correct, and the tolerances are too tight, I can see that all the expensive replacements in the world won't fix it.  But the tape-over-the-CEL thing isn't happening.  That worked for the Velvet Underground, but otherwise it sounds like pretty bad advice, as that way you don't see the blinks when additional codes are thrown.  And we don't have to do (periodic) emissions testing around here, so that's not a consideration, but being able to use one's cruise control - as well as getting decent mileage - is.

So I'd like informed opinions on the various fixes appearing around the 'net, because for the most part they appear to be on the edge of bogus.  For example:

Cleaning out your cat with soapy water.

A can of commercial cat cleaner in the gas tank.

Putting a spacer between the O2 sensor and the cat.

etc.

 

The spacer works great, but only for pre-2005 outback’s.