Mazda Protege DTC P0505

2 Jan 2015 | Author: | Comments Off on Mazda Protege DTC P0505
Mazda Protege

Questions and Answers

Mazda Protege DTC P0505

Q. Hi Vincent, I have a 1998 Mazda Protege LX, manual transmission and 77,500 miles. The Check Engine Light came on a few days ago, so we took it to a nearby Firestone. They told me:

The DTC is P0505 – Idle Control System Malfunction.

It’s expensive to fix, so instead they recommended various other tune-ups, spark plugs, ignition wires, distributor cap, fuel filter is what I remember. For good measure they suggested I get a new set of tires, too.

If the above recommended maintenance didn’t fix the problem, I’d need to get a new idle control speed valve.

From grilling the guy at the desk, they simply downloaded the code and did no more than that at all, so no verification of electrical circuits, etc. to make sure system was put together as it should be. Needless to say, I hightailed it out of there, minus $90.00 for their diagnosis but not intending to go back for any of their recommendations.

So, my questions:

The light is out; does that mean that the computer memory is erased, and therefore I cannot take it to get a second opinion?

If the light is out and does not come back on, does that mean it was a transient problem that does not need immediate/any attention?

Is there a legitimate cleaning/tune up to try, like cleaning intake manifolds, before replacing the idle speed control valve?

Thank you so much for your assistance.

A. You are a very smart lady Miriam. I would not have walked out of there, I would have run out. It is quite obvious he was more interested in selling work then addressing your problem.

Let that $90.00 be the last money you ever give them. It sounds like a Firestone Dealer I used to work for in New Jersey.

The owner was as shady as an oak tree. I saw him sell $1200.00 worth of front end work to a brand new Lincoln Continental with only 8,500 miles.

Anyway, to answer your questions, if they erased the codes, then it is gone unless the Powertrain Control Module (PCM) has detected the malfunction again. If the Check Engine Light (MIL) has not come back on since then, I wouldn’t worry about it too much.

Mazda Protege

If they didn’t erase the code then, even though the MIL is off, the code will still be stored. If the MIL hasn’t come back on, the malfunction is not present.

P0505 can be caused by a number of things, none of which will be repaired by replacing the tires. Below is a little information on DTC P0505.

The air intake system is composed of the air intake duct, air filter housing and the air intake tube, the big black tube going from the air filter housing to the intake manifold.

Check the air intake tube and make sure it is attached fully and firmly. Inspect the air intake tube for cracks or tears, especially in the valleys. Then check all the vacuum lines to be sure they are attached and in good shape.

Make sure the connector to the Idle Air Control Valve (IACV) is on and locked. Check the terminals to make sure they are clean and not damaged.

There is a maintenance you can do on the throttle chamber and IACV. Read my article Cleaning Throttle Bodies on what and how to do it.

Additional Information provided courtesy of AllDATA

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2003-2004 Vincent T. Ciulla

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