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Purchased a 2005 Magnum 5.7L. Couple of Questions...

504 Views 8 Replies 5 Participants Last post by  AutomaticWeapon1
Purchased a 2005 Dodge Magnum for about $2000 a couple of weeks ago. It needs a lot of front suspension components that have gone bad. Ordered a kit, and am planning on doing that this week. Not too bad from what I've seen on YouTube. I am also having a check engine light for codes P0420 (Catalyst System Efficiency Bank 1) and P1521 (Incorrect Engine Oil Type).

P1521 seems pretty straightforward. Oil change using correct weight oil (5w20). Any ideas on common points as to why the P0420 code goes on with these cars? Common points on the exhaust system to look at?

Also I have a spot on the top of the engine that is missing a bolt... Anyone know what this bolt is for? Here is a picture of it. Car appears to be stock; minus some aftermarket headlights that the previous owner wired in (I hate how people wire aftermarket things, they did an awful job). I'm looking into getting the shorty spark plug wires. I'm seeing the 8.2mm wires for sale. Is there a difference between the 8.2 and 10.4 Taylor shorty wires? That's really all I have thought about for minor mods. It's going to be a family car. Don't need any track/performance upgrades really lol.

Thanks all.
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Oil code is set after a 10min timeout when the oil pressor sense disallows the MDS system to engage after multiple attempts. In most cases, its because an end-user has somehow come to the ridiculous conclusion a higher viscosity engine oil offer better protection. It doesn't - nor will it ever!

P0420 can be many things:
  • Damaged muffler or leaks in the muffler.
  • Damaged exhaust manifold or leaks in the exhaust manifold.
  • Damaged exhaust pipe or exhaust pipe leaks.
  • A misfire in the engine.
  • Oil contamination in catalytic converter.
  • Faulty catalytic converter (most common).
  • Faulty engine coolant temperature sensor.
  • Faulty front oxygen sensor.
  • Faulty rear oxygen sensor.
  • Damaged oxygen sensor wiring.
  • Oxygen sensor wiring that is not properly connected.
  • Damaged oxygen sensor connectors
  • A leaking fuel injector.
  • High fuel pressure.
  • Use of the wrong kind of fuel (using leaded fuel instead of unleaded fuel)
The is no missing fastener; although the thread structure look strangely clean, nothing is attached there.
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