Belt Fraying and two CEL codes...2003 Mazda 6

Hi all! I am trying to purchase a 2003 mazada 6 v6 with 158k miles from my friend and wanted to make sure it was in working order.

It was throwing codes p2227 (egr boost sensor circuit performance) and p0300. After trying to remove the egr valve and failing (removed battery), it is no longer throwing the p0300 (might still in the future).

I removed the egr valve today and it was not as dirty as expected, so I suspect the sensor is bad even though it is not throwing a code yet (just a couple hours ago hooked the battery back up). Cleaned it anyway.

Also, I don’t know if it is the serpentine belt, but it is a belt on passenger side that runs lengthwise with the car, right behind the radiator. My friend just changed it a month ago, but the belt is already fraying. The tensioner sways quite a bit! I don’t know what this means, or how much it would cost to fix?

Any help in regards to the belt, especially, would be greatly appreciated! Thank you!

My friend said he replaced the pulley and the tensioner, so maybe it is a bearing of some sort? Or pulley misalignment?

It’s the serpentine belt. Your friend apparently didn’t do the job properly. Take it to a reputable independently owned and operated shop and have the belt and the tensioner changed properly.

The p0300 could be concerning, as it might be expensive to diagnose and/or fix. It means the ECM is detecting random engine misfires. Could be anything from among spark plugs, wires, coil packs, oxygen sensors, fuel injectors, valves, cats, cam or crank sensors, or even a defective computer.

One positive, it is also possible the p0300 is caused by the EGR problem, and once the EGR problem is fixed – which should be fairly easy for an experience mechanic – the p0300 may go away by itself.

Re the belt. If the pulleys are not all aligned in the same plane (think high school geometry), that can quickly ruin a new belt. Since the pulley and tensioner were replaced, it may be some shims got lost or something else is wrong causing the pulleys not to line up properly. Some shops have a laser gadget they use to test for proper pulley alignment. The belt problem can probably be fixed without too much trouble, but there may be some expense involved, perhaps considerable. Why guess. A tech just needs to do a visual inspection and determine what all is wrong.

Thanks for the input!

After the first time I disconnected the battery, and unsuccessfully tried to remove the egr, I have not had the p0300 code show up again (that was about 4 or 5 days ago). Is it possible then that it was just a computer error or a one off thing, or maybe it just hasn’t reared its head again?

Fingers crossed that cleaning the EGR fixed the other code.

I took it in to have it inspected previously, and they replaced the radiator fan and said it was pretty much good to go otherwise. They were a reputable mechanic shop, but then the a/c stopped working immediately after. Got it recharged at Pepboys and all seems good on that front so far.

I just wanted to avoid taking it to the mechanic again (but these codes weren’t coming up before they had it). Who knows, maybe they fixed one thing and it caused problems somewhere else?

Also, and maybe this is the wrong place to ask, but my friend wants me to give him $2000 and trade him my old camry with a bad oil pump (to trade in to a dealer). Pump leaks (but still drives) the day after I spent 400 on new brakes! So I am hesitant to have troubles again and wind up getting nickeled and dimed. The mazda will immediately need all new tires. With 157k miles, does this seem like a fair deal?

Btw, the car seems to be in excellent condition otherwise and he did take care of it

Have your friend sell his car to someone else and you buy a car from someone else. That way you will still have a friend.

+1 to oldtimer

+2 to oldtimer

BTW, it sounds like a good deal for your friend, but not for you.