Mechanics

PCM P0171 & P0174 HISTORY CODES

2000 Cadillac Seville • 135,000 miles

I know these code are telling my car is running lean, but every I check my OBD, they come up "History". If I clear the codes, they light up my "check engine light". I read different threads about checking vacuum hoses, to be honest guys, there's so many different hoses under the hood, I don't know what's what. I read also, not to worry about it if it reads "history". Well, it keeps turning my light on and it's annoying. Any suggestions?
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Thunder
June 21, 2012.



I didnt get to read the whole thread. Been sick guys.A history code means a fault happened with that circit. You cant really track it down because it happen so fast. Go in the obd sys. It stops on ecm data then push the high fan button for yes and low for no. Push yes to enter paremiters. Then push no keep pushing no untill u see o2 sensor. Drive the car a make sure the number is going up and down and not stuck on 1 number. Then youll no the o2 is swinging up and down.A history code is really no big deal. When its current then u can follow a code troble tree chart. To pin it down. Hope this helps.U could replaceing the o2 sensors. And see if its stops. Gl

Cadieman
Aug 13, 2012.
Read a little above your post cadieman now there asking why is the number 5 spark plug keep burning out?Also where it is and how to get to it?

Saturntech9
Aug 13, 2012.
Resestance in the connection to the plug.#5 I would replace the plug and ingnition wire.#5 is the 3rd plug on the front of the engine. Gl

Cadieman
Aug 13, 2012.
Ok guys, not to leave you in the dark. I took Betsy to the dealership. 1st problem was the fuel pump, instead of 45 psi I only had 30 psi. One fuel pump and regulator installed. 2nd. As for the fuel trim being lean, there was a vacuum hose connector sheared off by tires plus and a couple of gaskets needed replaced. 3rd (and finally), I needed the rear ignition coil and #5 spark plug replaced. Oh she runs like a dream now (let me knock on wood). Please don't anyone ask me how much this cost me, i'm still crying : ( I want to thank cadieman & saturntech9 for your help with this craziness. I called Cadillac the other day and told them I thought my gas gauge was broken, it was just I was wasting that much gas! Lol!

Tiny
Thunder
Oct 1, 2012.
Wow sounds like it would have been cheaper just take it to the dealer to begin with thats crazy. Also your are welcome thats what were here for.

Saturntech9
Oct 1, 2012.
Your right! I was expecting ~$750 -1000 bill. Lol the fuel pump alone cost me $539! They kept adding on, I had already committed myself. If I would have known it would have gonna cost me $2200 to fix it, i've would have went for the new Caddy ATS. Oh well, I guess I have wait till nxt yr.

Tiny
Thunder
Oct 1, 2012.
Oh the cts?I love those cars a expensive repair you had glad I do all my own repiars and all family and friends also that keeps me pretty busy with just those cars.

Saturntech9
Oct 1, 2012.
Not the CTS, the 2013 Caddy ATS. It's "suppose" to compete with the 3-series. Lol, we'll see.

Tiny
Thunder
Oct 1, 2012.
Wow that is a new model.

Saturntech9
Oct 1, 2012.
One thing I like to mention before we stop beating this dead horse; I was told the #5 spark plug was in the front of the engine. In fact, it is in the back (firewall side). That's why I had to replace the rear (firewall side) ignition coil it was burning out spark plug #5.

Tiny
Thunder
Oct 2, 2012.
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