How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Ron Z. Your Own Question
Ron Z.
Ron Z., - Dodge Tech -
Category: Dodge
Satisfied Customers: 18783
Experience:  18+yrs experience. State Inspector and Dodge Diagnostics
Type Your Dodge Question Here...
Ron Z. is online now
A new question is answered every 9 seconds

Dodge Caliber: My 2008 Caliber has the check engine light come

Customer Question

My 2008 Caliber has the check engine light come on and it stays on for about a day. Then the next day when I turn the vehicle on it does not come on. It started doing this about 3-4 days ago and I cannot get into the dealer before next week to get it checked. Will I do permanent damage to the vehile by driving it until then or is this something that happens commonly.
Submitted: 5 years ago.
Category: Dodge
Expert:  Ron Z. replied 5 years ago.

Welcome to! My name is DriveFast71(Ron) and I will do my best to answer all of your questions completely and accurately.


When the Check Engine light comes on, this is the on-board computer's way of telling you it sees a problem in one of the monitored systems. Unfortunately, there are litterally 100's of parts and sensors monitored in various systems, and to take a "guess" as to which part/sensor in which system is faulty, is virtually impossible. However, if you are not experiencing any drivability issues such as skipping, stalling, shifting problems, etc, then more than likely, the problem is going to lie in the EVAP (emissions) system. Very commonly, this could be a faulty, loose or missing fuel cap or even putting fuel in while the vehicle is running. Check the cap for any cracks in the rubber o-ring on the underside. Check the fuel filler neck for any signs of chips or debris. Check under the vehicle, around the area of the fuel tank and the EVAP canister looking for any vacuum lines that have dry-rot cracks, holes or loose/missing connections. If these all check out, then the best thing to do at this point is to have the "p-codes" read from the on-board computer. These p-codes are what is used as a "starting point" for the diagnosis and will tell which part/sensor in which system has the fault. There isn't a Mechanic on the planet that can tell you what is wrong with the vehicle just by "looking" at the Engine Light. Every single Mechanic's first course of action WILL be to obtain the p-codes. Once you get these p-codes you can more accurately and efficiently diagnose the problem and then make the repair. You can have these p-codes read FREE (except in California) at any local "big chain" part store (ie. AutoZone, PepBoys, Advanced, etc). If you still need help after retrieving the codes, you can bring them here, and any of our Techs can walk you through the diagnostic procedure, and then even help you make the repair if you feel confident enough to try.


As long as you are not experiencing any performance or driavability issues, it's safe to drive the vehicle. I do recommend at least getting the codes read, just to make sure it's in a system that cannot harm the engine. If for nothing else- peace of mind.

Expert:  Ron Z. replied 5 years ago.
In many instances, emissions systems must fail diagnostic tests more than once before the PCM illuminates the MIL. These tests are known as 'two trip monitors.' Other tests that turn the MIL lamp on after a single failure are known as 'one trip monitors.' A trip is defined as 'start the vehicle and operate it to meet the criteria necessary to run the given monitor.'

Many of the diagnostic tests must be performed under certain operating conditions. However, there are times when tests cannot be run because another test is in progress (conflict), another test has failed (pending) or the Task Manager has set a fault that may cause a failure of the test (suspend).

  • Pending Under some situations the Task Manager will not run a monitor if the MIL is illuminated and a fault is stored from another monitor. In these situations, the Task Manager postpones monitorspending resolution of the original fault. The Task Manager does not run the test until the problem is remedied.

For example, when the MIL is illuminated for an Oxygen Sensor fault, the Task Manager does not run the Catalyst Monitor until the Oxygen Sensor fault is remedied. Since the Catalyst Monitor is based on signals from the Oxygen Sensor, running the test would produce inaccurate results.

  • Conflict There are situations when the Task Manager does not run a test if another monitor is in progress. In these situations, the effects of another monitor running could result in an erroneous failure. If this conflict is present, the monitor is not run until the conflicting condition passes. Most likely the monitor will run later after the conflicting monitor has passed.

For example, if the Fuel System Monitor is in progress, the Task Manager does not run the catalyst Monitor. Since both tests monitor changes in air/fuel ratio and adaptive fuel compensation, the monitors will conflict with each other.

  • Suspend Occasionally the Task Manager may not allow a two trip fault to mature. The Task Manager willsuspend the maturing of a fault if a condition exists that may induce an erroneous failure. This prevents illuminating the MIL for the wrong fault and allows more precise diagnosis.

For example, if the PCM is storing a one trip fault for the Oxygen Sensor and the catalyst monitor, the Task Manager may still run the catalyst Monitor but will suspend the results until the Oxygen Sensor Monitor either passes or fails. At that point the Task Manager can determine if the catalyst system is actually failing or if an Oxygen Sensor is failing.

MIL Illumination

The PCM Task Manager carries out the illumination of the MIL. The Task Manager triggers MIL illumination upon test failure, depending on monitor failure criteria.

The Task Manager Screen shows both a Requested MIL state and an Actual MIL state. When the MIL is illuminated upon completion of a test for a good trip, the Requested MIL state changes to OFF. However, the MIL remains illuminated until the next key cycle. (On some vehicles, the MIL will actually turn OFF during the third good trip) During the key cycle for the third good trip, the Requested MIL state is OFF, while the Actual MIL state is ON. After the next key cycle, the MIL is not illuminated and both MIL states read OFF.