Mazda Protege DX - Codes P0506 and P0715

My first thought would be your crankshaft position sensor has gone bad, but I would expect that to throw its own code as well.

Is the car running ok? Or does it "chug" at idle? If it still runs smoothly my thoughts would lean toward a malfunction of a transmission mounted sensor. However I would expect the speedometer to perform erratically.

Someone with better knowledge of mazda's sensor set-ups and functions may be able to help more readily. Try googling the codes and see if they point to one specific sensor. It may be as simple as cleaning the sensor connections from the spilled oil, or at worst replacing a $20-$100 sensor.

Best of luck.

-T

edit: Check the Idle Air Control for oil contamination too, it is usually located next to the throttle body, or on the intake manifold, and can be found by tracing the intake tubing in the path that bypasses the throttle body. If it has been gunked up it might throw both those codes.

Ok, you need to put everything into sequence. Please number the highlighted events.

I have owned the car for a year and a half and have not had the transmission flushed. I will admit I was a MORON and left the oil cap off and did not notice until the car was spewing oil everywhere. We did replace the belts recently and cleaned the engine about a week ago to try and clear off some of the oil. We changed the belts because of a high pitch screetching noise and noted the alternator belt was worn.

Did you have the error codes before the MORON event? If not, when?

The rest doesn't matter.

I had not had any codes prior to my Moron moment. The cap and cleaning incidents were last week and the codes appeared yesterday.

Thank you,

Angela

You can usually cure a " high pitch screetching noise" by turning the radio up all the way.

The oil did it, more than likely. You may need to replace the sensor. There are real mechanics here, I'm not one. They can tell you where it is.

Good Luck.

If the oil managed to get drawn to the air cleaner element, it might be restrictive now. That may, or may not cause the codes you see to set. check the air filter, and replace if in doubt. If I were you, I would clear the codes, and see if they reset. Do that after the air filter, if the filter is bad. Try that, and let us know.

(LL is a mechanic. He is just too embarrassed to admit it publicly)

Welcome to the insanity.

This P0506 code is one that's sometimes triggered on vehicles that have electronic throttle control. That is, they don't have a regular throttle cable from the accelerator pedal to the engine. They rely on sensors and electronics to control the throttle. In this case, the P0506 DTC (diagnostic trouble code) is triggered when the PCM (powertrain control module) detects an engine idle speed that is lower than the desired (pre-programmed) RPM.

Most likely the only thing you'll notice is the idle speed is lower than normal so it will likely be rougher. There are potentially other symptoms as well. Of course, when trouble codes are set, the MIL (malfunction indicator lamp, a.k.a. the check engine light) illuminates.

A P0506 DTC trouble code may be caused by one or more of the following:

• A vacuum leak
• An air restriction in the intake air path or exhuast
• A faulty positive crankcase ventilation (PCV) valve
• Damaged/failed/dirty throttle body
• Internal engine problem
• Failed PCM

This DTC is more of an informational code, so if there are any other codes set, diagnose them first. If there are no other codes, inspect for vacuum leaks, restrictions, and damage. If there are no symptoms other than the DTC itself, just clear the code and see whether it returns.

P0715

Very easy diagnostic and replacement of TSS (aka Pulse Generator) on our Proteges. Part located directly on top of ATX housing a few inches left of engine mount and under airbox. You can't miss it! Its electrical harness has two terminals.

1) Unclip and separate wiring harness on the part. Check resistance between the two terminals on the sensor: should be 250-600 Ohms on your multitester. If not, replace Pulse Generator (turbine speed sensor);

Nice informative answer. My question to you is this. If the engine speed has become low for whatever the reason, would the TSS recognise the lower speed as out of range, and set the code?

Possibly it could show a fault if the loss in idle speed was great enough and if I'm not mistaken the idle speed would have to drop about 25% which would mean that with an normal idle of 750 it would have to be idling at about 550 and would have to remain at that lower speed until the sensor reached its threshold count to set the code. The chances of it holding that rpm for the period required would be highly unlikely. You must realize that the tss sensor feeds it data to the PCM and compares that reading to the Ignition pulse count and if they remain out of sync then the 715 code would set although I have never seen that scenario happen in real life it is theoretically possible. Hope that answers your question but my first step would be to check the wiring and make sure that you check for corrosion in the plug and sensor terminals and then check the resistance of the tss sensor.

Thanks. It seems to me that many times one problem will set related codes. And being that both of these were rotation counting sensors, I was wondering.

Thank you very much! We are going to work on the car today. Very helpful and descriptive.

For code PO506 just gently clean your throttle body, scrape the carbon deposit in it. also replace your spark plug at the same time and erase the code. Remove your negative battery cable within ten minutes to reset.