Jeep 4.0L Index of Articles

In this tutorial I'm gonna' show you how to test the throttle position sensor (TPS) on your 4.0L Jeep Grand Cherokee (Cherokee, Wrangler) without a scan tool. This is a... [read more]

A trouble code P0135: O2 Bank 1 Sensor 1 Heater Circuit Performance on your Jeep Cherokee (Grand Cherokee, Wrangler) lets you know that there's a problem with the heater... [read more]

This article will present you with the four most common ways to test for a blown head gasket on a Jeep 4.0L inline 6 cylinder engine. All four are very simple and easy... [read more]

The fastest and the most accurate way to test the manifold absolute pressure (MAP) sensor on your 4.0L equipped Jeep Cherokee (Grand Cherokee, Wrangler) is to bench-test it... [read more]

An engine compression test is fast becoming a key test in diagnosing a hard to troubleshoot misfire condition. In this tutorial, you'll learn how to do the engine... [read more]

Testing the starter motor, to see if it's the cause of the no crank condition on your Jeep, is not that hard. As a matter-o'-fact, testing the starter motor, to see if... [read more]

The manifold absolute pressure (MAP) sensor on your 2.5L, 4.0L Jeep Grand Cherokee, or Wrangler, or Cherokee, can be tested with a multimeter and a vacuum pump. You don't... [read more]

This tutorial will help you to diagnose the Pulse Width Modulated (PWM) fan relay on the 1999-2003 Jeep 4.0L Grand Cherokee SUVs and/or the codes P1491 (Radiator Fan Control... [read more]

The upstream oxygen sensor on your OBD II equipped Jeep 4.0L SUV can be tested, and in this article, I'll show you how in a step-by-step fashion. This tutorial will help... [read more]

Fuel injectors rarely go bad, but when they do, they will cause the engine in your Jeep 4.0L Grand Cherokee (or Cherokee or Wrangler) to miss and/or idle rough. The... [read more]