wolflady

I just bought a 99 Cherokee Sport 2 months ago. I ran great then check engine light came on had a friend use their code scanner on it and it come up with codes P1492 and P1505
It is idling high and has problems starting used to only be every once in a while now it's daily or won't start at all. I've had the battery checked and it is good. Would these 2 codes cause it to not start? This is my first Jeep. It has lost power also and when I stop the oil pressure also drops. I'm familiar with cars and trucks and know it's not always normal for the oil pressure to just drop as it has. Any and all help would be great I'm at my wit's end an need it to get it back on the road as I have no other way to get around. Thank you!

Jim Malcolm

The P1505 code is for the Idle Air Control Valve. It allows the computer to manage the rpms of the engine while the throttle is closed. It bolts to the side of the throttle body. Easy remove and replace fix.

P1492 is for the Battery Temperature Sensor, which allows the computer to charge the battery faster when it's cold than when it's hot. Not the end of the world, get it running first. Another easy remove and replace fix; it's located under the battery tray.

Oil pressure will drop in most engines going from a few thousand rpm down to idle. The important question is, how low is it dropping?

cruiser54

Try this:CRUISER'S MOSTLY RENIX TIPS

THROTTLE BODY AND IAC CLEANING

OCTOBER 30, 2015 SALAD 24 COMMENTS
Originally by TJWalker of CherokeeForum & JeepForum



The Idle Air Control (IAC) is mounted on the back of the throttle body (front for ’87-’90).

The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is retracted, the air control passage flows more air which raises the idle speed. When the valve plunger is extended, the air control passage flows less air which lowers the idle speed.

Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea. This should be part of a normal tune-up procedure and whenever idle/stalling issues are present.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

1. Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a Torx driver (2 bolts; one can be kind of hard to get to). On ’91 and later, it may be easier to just remove the whole throttle body. Be sure to use a new throttle body to manifold gasket when reinstalling.
2. “Gently” wiggle out the IAC from the throttle body. Gasket/O-ring on the IAC can be re-used if it is not damaged
3. Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and oxygen sensors. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.
4. Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner.
5. It is also a good idea to clean the entire throttle body bore itself, the butterfly valve inside of the throttle body and it’s edges, and all associated linkage as long as you have things disassembled.

Revised 1-31-2016

lawsoncl

Welcome to the forums. X2 on Cruisers advice on cleaning the throttle body. I'll also mention that it's pretty common for the oil pressure sensor to go bad. Probably more frequent than an actual oil pressure problem.