Cleaning or replacing the EGR valve and clearing the code does not fix the vehicle because the code usually returns. A brand new valve takes only about 50 milliseconds to open but an older valve may take up to milliseconds or longer — which is not long enough to cause a real NOx emissions failure but is long enough to trip a fault code. The fix in this instance is to reflash the PCM with new instructions that allow more time for the EGR valve to respond.
Another example are rich codes that may appear on some late-model GM vehicles. The problem here is that the original OBD II self-diagnostic programming does not allow enough leeway for changes in intake vacuum that occur as the engine ages.
The cure is to flash reprogram the PCM to compensate for the drop in vacuum. When vehicle manufacturers calibrate the onboard diagnostics to meet federal emissions standards, they have to draw the line somewhere as to what operating conditions might cause emissions to exceed federal limits 1. That is the threshold where a fault code must be set and the Check Engine light must come on.
Depending on the application, the vehicle manufacturer may even set the limit a little lower just to be safe because the last thing any OEM wants is an expensive emissions recall. The best advice when confronted with a troublesome code that keeps coming back or seems to set for no apparent reason is to check for any technical service bulletins that may have been published.
Chances are it might be a programming issue that requires a reflash to fix. Something else to keep in mind with respect to many late-model flash reprogrammable PCMs: if you replace the PCM for any reason, the replacement unit may have to be reflashed before it will start the engine!
Some modules are plug-and-play, and are preprogrammed by the dealer or aftermarket parts supplier so they can be installed ready-to-go. But many need vehicle specific calibration information to run properly. This may require downloading old calibration information from the original PCM if possible and reloading it into the replacement PCM, or getting updated calibration information from the vehicle manufacturer to install in the new module.
If you are buying a reman PCM from an aftermarket supplier, they may be able to program it for you. The information they need to do this includes your year, make and model of vehicle, engine size, vehicle identification number VIN , the type of transmission manual or automatic , the emissions type federal certification or California , and other options that may affect the calibration of the PCM.
Your other option is to have a car dealer or repair shop reflash the computer, or attempt it yourself.
Historically, car dealers have been the only ones who had access to the tools and software needed to reflash PCMs. Thanks to the passing of Senate Bill in September , vehicle manufacturers must now make this technology available to independent repair shops and individuals at reasonable cost. Starting in , flash reprogramming procedures also had to conform to SAE J standards that allow the use of aftermarket scan tools or similar pass-through devices.
Other items that are needed include a cable to connect the laptop to the scan tool or J pass-through device, and a cable to connect the scan tool or J pass-through device to the OBD II connector on the vehicle. You will also need a battery power supply source or charger that can maintain a steady constant voltage to the vehicle during the reflash procedure.
You do NOT want any voltage drops for fluctuations during the reflash because it may screw up the programming of the PCM. For older GM applications, you can use a Tech 2 scan tool or Vetronix scan tool or other aftermarket J pass thru tool. Module 16 Item no. Module 17 Item no. Module 18 Item no. Module 19 Item no. Module 20 Item no. Module 21 Item no. Module 22 Item no. Module 23 Item no. Module 24 Item no. Module 25 Item no. Module 26 Item no. Module 27 Item no.
Module 28 Item no. Module 29 Item no. Module 30 Item no. Module 31 Item no. Module 32 Item no. Module 33 Item no. Module 34 Item no. Module 35 Item no. Module 36 Item no. Module 37 Item no. Module 38 Item no.
Module 39 Item no. Module 40 Item no. Module 41 Item no. Module 42 Item no. Module 43 Item no. Module 44 Item no. Module 45 Item no. Module 46 Item no. Module 47 Item no.
Module 48 Item no. Module 50 Item no. Module 51 Item no. Module 52 Item no. Module 53 Item no. Module 54 Item no. Module 55 Item no. Module 56 Item no. Module 57 Item no. Only an updated calibration can be loaded into the vehicle computer. There is no going back to an earlier version. Turn the ignition OFF, then disconnect the scan tool. With Ford vehicles, a somewhat different approach is used. First, you need the vehicle calibration ID number. This can be found on a sticker somewhere in the engine compartment.
Next, you have to figure out if there is a newer calibration available. This requires going to the www. The next screen will list all of the possible calibrations by PCM part number. You then have to buy a one-day subscription before you can download the software to your PC that is necessary to do the reflash. You will also need a J pass thru tool to do the reflash. With Ford, the calibration software that will go into the car is not stored on the PC.
The software that you downloaded only facilitates the transfer of the new calibration from Ford into the car. First you go to the www. If the vehicle needs a update, you go back to the Chrysler website, pay their access fee, and download the new software to your PC. Then you transfer the software from the PC to a scan tool or J pass-through tool to install it in the vehicle. Here is a sample of the flash reprogram procedure a Chrysler dealer would use.
Once the lines of communication are open, the VIN is displayed on the scan tool. This does not indicate a problem and the codes can be erased after the flash reprogramming procedure has been completed. The technician is also supposed to attach a label to the PCM with the reflash part number and date indicating the PCM has been reflashed.
Anyone who has ever experienced a crash while installing new software on a PC knows it can cause real problems. Chrysler issued a TSB that deals with how to recover from a flash reprogramming failure.
If the process crashes, recheck all the cable connections to assure good communications and reinitialize the flash procedure. If you get an error message again, you probably selected the wrong controller type try again!
Doing your own flash reprogramming is not without risk. Any number of things can go wrong during the installation process which may result in an incomplete update or a frozen PCM. In some cases, the software must then be copied to a flash card which is then plugged into a scan tool or J device for installation into the vehicle. In other cases, the software is fed through a cable or wireless connection to the J device so it can be installed in the vehicle.
If you lose the internet connection, you will have to start the installation all over again -- and hopefully it will work. Losing the connection part way through an installation may royally screw up the PCM! The flash procedure can takes from a few minutes up to an hour depending on the file size of the software you are installing. The newer and more complex the vehicle, the longer it typically takes to flash the PCM. Only an updated calibration can be loaded into the vehicle computer. There is no going back to an earlier version.
With Ford vehicles, a somewhat different approach is used. First, you need the vehicle calibration ID number. This can be found on a sticker somewhere in the engine compartment. Next, you have to figure out if there is a newer calibration available. This requires going to the www. On the next menu page that appears, scroll down to the link for "Latest Calibration Information. The next screen will list all of the possible calibrations by PCM part number.
Find the part number that matches your PCM and that's the latest calibration you need. You then have to buy a one-day subscription before you can download the software to your PC that is necessary to do the reflash. You will also need a J pass thru tool to do the reflash. With Ford, the calibration software that will go into the car is not stored on the PC. The software that you downloaded only facilitates the transfer of the new calibration from Ford into the car.
In other words, it is a "live" procedure that requires a continuous unbroken internet connection until it has finished. Chrysler's flash procedure is sort of a cross between GM and Ford's procedures.
First you go to the www. If the vehicle needs a update, you go back to the Chrysler website, pay their access fee, and download the new software to your PC. Then you transfer the software from the PC to a scan tool or J pass-through tool to install it in the vehicle. Also note, many Chrysler PCMs require a re-initialization procedure after a flash.
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