Codes p1507 and p1505 IAC valve

The P1507 code means that the engine idle is out of factory specification. Sometimes the Idle Air Control (IAC) may have carbon built up.

2002 Hyundai Elantra DTC P1505 AND P1507 Engine Performance same as kia

Possible causes
- Faulty Idle Air Control (IAC) valve
- Idle Air Control (IAC) valve harness is open or shorted
- Idle Air Control (IAC) valve circuit poor electrical connection
What does this mean? Tech notes
The P1507 code means that the engine idle is out of factory specification. Sometimes the Idle Air Control (IAC) may have carbon built up. Disconnect the car battery, remove the valve, clean, re-install valve, and drive the vehicle for about 5 minutes with the headlights and A/C ON to get the idle relearned.
If the problem persist, the IAC valve may need to be replaced.

Read more: http://www.engine-codes.com/p1507_ford.html#ixzz3sFPyZe00

P1507 - Idle Air Control (IAC) Underspeed Error This DTC is set when the PCM detects engine idle speed that is less than the desired rpm.

• IAC circuit open
• IAC circuit short to PWR
• VPWR to IAC solenoid open
• Air inlet is plugged
• Damaged IAC solenoid
• Damaged PCM

• The IAC solenoid resistance is from 6 to 13 ohms
• Disconnect IAC valve and look for no change in engine rpm as an indication of a stuck or damaged valve

Possible causes for P1505 & p1507
Faulty Idle Speed Control Actuator valve, harness is open or shorted, Idle Speed Control Actuator valve circuit poor electrical connection. No the codes are not related to the EGR. P0198 is related to the engine oil temperature sensor. By the way you should use a meter as supposed to a test light. The test light will not be able to measure 5 volts reference or voltage drops. However I would try replacing the affected parts based on the codes and the info you've provided. Good luck.

possible problems

Vaccuum leak
failed IAC valve
open or short
air inlet plugged

P1507 means "Idle Air Control Underspeed Error". It can be most commonly caused by a vacuum leak, a damaged Idle Air Control (IAC) assembly or a stuck IAC valve that needs cleaning. Essentially, your engine isn't idling at high enough according to your computer's programming parameters. Many times this shows up in colder weather as you try and start your vehicle. It will usually die unless you put your foot on the gas pedal and raise the RPM's. I have also read where a clogged air filter might be the problem. I would try cleaning your IAC valve first.

Repair information for the OBD-II trouble code P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

Answer P1507 means "Idle Air Control Underspeed Error". It can be most commonly caused by a vacuum leak, a damaged Idle Air Control (IAC) assembly or a stuck IAC valve that ...

sorry but their are no diadnostic codes with this number in the manufacturers codes i have
P0505....Idle Control System
P0507....Idle Control System RPM Higher Than Expected
but i have found these generic codes for you if they help

P1507 is "Idle Air Control System Underspeed Error". This code indicates a problem with the Idle Air Control (IAC) valve assembly, harness wiring for the IAC or the Powertrain Control Module. So checking the IAC next is the most logical step.

There are to many things that can cause your blazer from idling.
Go to Auto Zone or Parts Source and they can scan your blazers computer. There should be a DTC code which should make you understand why your having the problem.
I believe they both scan for free and may have the parts you need to replace and give you the how to do it your self instruction for the repair:
 Good luck and hope this helps, here are some codes that control ther idle speed of your engine. It's the air idle control valve that may have gone bad or it just may be a dirty or stuck EGR valve. The scan should let you know.

P1505 Idle Air Control At Adaptive Clip

P1506 Idle Air Control System Over speed Error

P1507 Idle Air Control System Under speed Error

P1508 Idle Air Control (IAC) System - Low RPM