The codes appeared right after my jeep started idling rough once it warmed up. Not worried about the code 12. It's a 93, 4.0, ax15.

 

Code 13: Map sensor pneumatic signal---no variation in MAP sensor signal is detectred or no difference is recognized between the engine MAP reading and the stored barometric pressure reading.

1. Remove vacuum line leading to the MAP sensor. Be darn sure that line is pulling good vacuum. Your MAP sensor won't work without vacuum.

2. Inspect every inch of wiring related to the MAP sensor.

3. If #1 and #2 above check out, I'd recommend you replace your MAP sensor.

 

Just by looking, that hose is wasted. The one towards the end of the block.

 

That is a CCV hose (crankcase ventilation) and while it may be a good idea to replace all of your CCV hoses and fittings, this is not likely related to your code 13.

You always need to focus on the code and where it leads you. And your code is a MAP sensor code.

 

The one heading to and from the sensor is fine. The code is still there but the engine light is still on, but I haven't reset the CPU yet.