SES Light

[Aviator327]

The Service Engine Soon light came on yesterday morning. Took it to the dealer this morning and the code that came up was PO420 (Catalytic converter). They didn't have one in stock so it is being shipped from Lansing, MI. just curious if this is a common issue for the Bonneville? Current milage is 51,000mi.

[1fatcat]

It is, but alot of times the converter fails because of a rich running condition. Take a real good look at your fuel pressure regulator. Also, cleaning the MAF sensor never hurts.

[00Beast]

Make sure this list is up to date.

Brand Suggestions are in the parentheses.

• 1987-2005 Bonneville / Buick 3800 Maintenance List
  
  Run Seafoam through gasoline and intake every 5,000 miles. One pint of Seafoam in a half tank of fuel is a good mix. The intake is optional, but recommended.
  
  Grease: Ball Joints, Tie Rods Every 8-10k ( Green Grease recommended)
  Air Filter Every 15k (Amsoil EaA, Purolator PureONE)
  PCV Valve Every 30k
  MAF Sensor Element Cleaning/TB Cleaning Every 50k viewtopic.php?f=48&t=1661
  Fuel Filter Every 15-25k (Purolator, AC Delco, WIX)
  Spark Plugs Every 30-50k (NGK TR55 or Autolite 605) (Never Bosch)
  Ignition Wires Every 30-50k (Napa Belden, AC Delco, Autolite Pro, NGK) (Never Taylor or Bosch)
  Oil & Filter Every 5-6k or Every 6 months (Mobil1 or Amsoil)(Mobil1, Purolator PureONE, Amsoil EaO or WIX) (Never Fram) viewtopic.php?f=45&t=214
  *Conventional Oil Every 3k/3 months(Pennzoil with a WIX (Napa), Delco or Purolator filter)
  Transmission Flush Every 15-20k (Always make sure filter is changed when flushed)
  Cooling System Flush Every 25-50k or 3-5 Years (Peak or Prestone Green Coolant Only) (Never Dexcool)
  Oxygen Sensor Every 80-100k (30k for non-heated) (AC Delco or Denso) (Absolutely never Bosch) viewtopic.php?f=48&t=794
  Accessory Belt Inspect every 15k, replace every 100k, or as needed
  Cabin Air Filter Inspect and Replace every 15k, or as needed in dusty conditions. (Note: 00+ Only)
  Evap Core Cleaning Whenever Needed (Note: 99 and older only) viewtopic.php?f=45&t=2432
  
  *Special Considerations*
  All 3800s, LG3, LN3, L27, L36, L26, L67 & L32, especially important on vehicles factory installed with orange Havoline Dexcool Antifreeze/Coolant: http://www.dex-cool.net/
  Lower Intake Manifold Gasket Replacement, every 80-100k (ignorance of this can allow coolant to enter your engine oil, this happening can cause irreversible lower engine damage, requiring replacement of subject engine)
  
  Series II, Naturally Aspirated, RPO:L36:
  Upper Intake Manifold Plenum Replacement, Every 80-100k (ignorance of this can allow coolant to enter your intake manifold, possible damage to occur can be hydrolock, irreversible damage to emissions devices, misfires, etc. Most times, engine replacement is required if ignored long enough.) viewtopic.php?f=53&t=1061
  
  Series I, II, III RPO Code L67 & L32:
  Change Supercharger Oil; Every 30-50k. (Intense Racing or GM Dealer) viewtopic.php?f=56&t=1690
  Supercharger Belt; Inspect Every 15k, Replace Every 100k or as needed.

[1fatcat]

Not trying to nit-pick, but some of the things on your list seem to be recommended a little too soon. For example:
Air filter: a paper air filter usually lasts about 40,000+ miles under normal driving conditions.
PCV: a pcv will usually last about 80,000+ miles
MAF cleaning: depends on your air filter...an oiled filter will require more frequent MAF cleaning
Fuel filter: about 50,000+ miles
Spark plugs: around 50,000-90,000 miles depending on if they are platinum or not
Plug wires: 80,000-100,000+miles
Transmission fluids: I ain't touching that with a 10 foot pole!
Coolant: 50,000+ miles
Oxygen sensor: only when it fails
Drive belt: when it is badly cracked
Supercharger oil: 100,000+ miles

OK, bring on the flame thrower!

[bonnevillain]

I agree some of those things can last a lot longer than listed, but they are also pretty cheap (or free!), and it certainly can't hurt. I also disagree with only changing oxygen sensors when they fail.. they do go "sorta bad" before they throw a code, and mileage usually suffers.

[00Beast]

The mileages may not be 100% accurate, but it's better to be safe than sorry.

[01bonneSC]

The mileages may not be 100% accurate, but it's better to be safe than sorry.

x2 its called prevenative maintanance, and ur car will run better, for longer when u change things before they start reaching the end of their life

[Aviator327]

Thanks for the feedback guys.

[bonnie02rkt]

I had the same ongoin problem for about a year and a half and could never get any help with the issue. I replaced the cat first and about 600 miles later the same code came up... shortly after i replace sensor after sensor and could never get rid of the code. I even replaced the ECU! Then I finally said the hell with it and got the ecu from intense and got the code deleted! I assume I never really fixed the problem!

[bonnevillain]

the rear 02 going bad could probably cause this also.

[01bonneSC]

the rear 02 going bad could probably cause this also.

x2! beat me to it!
Yeah if the catalyst sensor isnt working properly, then it would think the cat is bad.

[Aviator327]

The dealership ordered it on Monday and hasn't got here yet. They said the cat converter had to be shipped by truck because of its length. He said the converter goes all the way to the back and ties into the exhaust system.

[00Beast]

Uh, no. The converter is about a foot in length. Would they have ordered the resonator by mistake??

[Aviator327]

Who knows. That's what the service rep told me yesterday. I thought the converter was short.

[01bonneSC]

Shoulda picked up this and just headed to the exhause shop...
http://www.3800performance.com/Merchant ... t_Count=27

[1fatcat]

Cats are covered under factory warranty for 8 years or 80,000 miles. They SHOULD have ordered you the factory replacement cat, which is pretty long on your car. It may even go all the way to the tail pipe?

[harofreak00]

Its possible that they had to order a complete exhaust system. The OEM system doesn't have replaceable joints.

[bonnevillain]

Cats are covered under factory warranty for 8 years or 80,000 miles. They SHOULD have ordered you the factory replacement cat, which is pretty long on your car. It may even go all the way to the tail pipe?

no. The factory cat is only about a foot long.

I think Haro may be right though, They would have to cut it out and weld in a new one, which they may not want to do.

[white06lacrossecxs]

When the cat on my park avenue went bad the entire exhaust from the cat back had to be ordered because it is ordered as one piece. We had an aftermarket one installed instead. The dealer quoted $600 for the part.

[1fatcat]

I have worked for a few dealers and we never did a weld in replacement if it was covered under warranty. It got the same assembly that came with it new.