Hi all- I am very new to this forum. I have a 2004 Tribute 3.0L 24V DOHC V6 which runs absolutely perfectly and does not fault with the AC running nor when the heater is on. It runs at normal temp and has thermo fans that cut in and out correctly. My problem is that the Check Engine Light keeps coming on. I had it to a mechanical workshop who told me the MAF needed to be replaced so it was done. Light came back on with in 5 kms of driving. Then the next mechanical workshop pulled up a code saying it was an EGR Valve fault code PO401 - they cleaned the EGR and replaced a fuel pressure sensor - Check engine light again went off until I drove it for approx. 10 kms. Took it back to them and was told I needed a new coolant bottle and cap so it too has been replaced which I did myself and after disconnecting the neg battery terminal I then drove the vehicle 32 kms stopping and started a few times, whilst at running temperature and the light stayed off. I thought - hey presto fixed !! But no, it continues to come on - sometimes I run it idling for an hour and no light appears, turn it off and on a few times and still no light reappears. The next day I can go out and start it and within minutes the Check engine light comes back on again but it still runs like a new engine. I realized that one of the mechanical workshops had not refitted the air cleaner cover correctly when they changed the air filter so thought perhaps that was the problem but nope - I refitted that correctly and the light still comes on. Every time I disconnect the Neg battery terminal it goes out okay, but continues to come back on at different intervals of times running or kms driven but doesn't miss a beat

 

Ok so disconnecting your battery only turns off the dash engine check light really nothing more. You need to in the future seek a shop that has a Certified Automotive Technician. The information you are posting is indicating a shop that does not really do well with diagnostic work and are randomly changing what may simply be guessed problem parts.

There is nothing that indicates that any of the shops even checked your I/M Monitors.

What you are describing about the check engine light is your problems causing them were never found and resolved and re-examined in a permanent file in the ECU until you did several engine cycles and the ECU via sensor information that the problem still existed and generated the check engine light again.

My suggestion is stop replacing or having parts replaced before they are confirmed failed. Choos a better service shop and discus with them what the previous shops did?

Oh suggest not disconnecting your battery anymore until you get better information about your DTCs. While you are at the next shop have them also health test your battery. You find although not the cause of your current issues, but the battery may be starting to go bad? But at least have it checked.

 

Welcome to the forum

 

Thanks Callisto. Forgot to mention that I have also replaced the Battery 😊😊 The workshops I have taken to are supposedly reputable ie Ultra Tune and Auto Masters whom I thought SHOULD be able to at least diagnose correctly with their scanning tools. I am having trouble understanding why 'the check engine' light keeps coming on, when absolutely nothing is giving me any indication that the vehicle has a problem. I am feeling lost ATM, my husband (who was a fully qualified Mechanical Technician) whom passed away recently, would have had this sorted in a jiffy - I am now in a position of having to sell the vehicle, but obviously do not want to do so until I can sort and clear this error permanently. I realize it could be a number of different things but just REALLY thought an OBD scanner would at least point my in the right direction. I am considering buying my own tool and checking it myself at different stages of engine operation ???? Although an old vehicle it is in exceptionally good condition except for this damned light issue. Thanks again and I hope you or someone else on this forum is able to help ,me solve

 

UPDATE Question: This morning I started the vehicle - all good - and no check engine light on.
I then (with the engine off) , disconnected the MAF sensor, started the vehicle and the engine continued to run fine for a long time , allowing temp to be almost operating temp, again with no check engine light coming on.
Tuned engine off and restarted (still with MAF disconnected) the check engine light came back on then, in under a minute, but engine continues to run as smooth as - no missing or anything.
Next, I refitted the MAF sensor - check engine light remains on.
Allow the vehicle to go back to cooler temp for a couple of hours - restarted the vehicle (with the MSAF still connected) and the check engine light remains lit on the instrument panel.
I have just read a few posts that say - the engine should not run if/when you disconnect the MAF sensor - IS THAT CORRECT INFORMATION ??
Now starting to wonder if the workshop actually did replace the MAF sensor or if I have been ripped off.

 

Changing the battery does not mean it is good. Everyone assumes “new” and it is good.

The internet is full of poor advice that always simply by the odds is correct but really it does not work that way in the real world or a shop. If your husband wore an ASE shirt and was a certified Auto technician then he knew the steps.
Your test of the MAF is not conclusive as a bad sensor, and the proper testing is the MAF itself . Not trying to trick the ECU which receives input from several sensors that can send operating perimeters that you experiment the MAF may have been already normal if the engine and ambient were close.
Nice try though , but not really conclusive. And I would not rush to buy a new MAF, my guess is you can run the same experiment with the same results.
Of you can look at the I/M monitors see which ones are in fault and there will be at least one or more. Then note the correct DTC you find. Reset both your monitors and current DTC. Do this at night so you start the next day fresh in a drive cycle. At the first engine check light as soon as safe to do so pull over and retrieve the DTC(s). As well check and note which I/M monitors are still in fault/ not ready. This may help better to DIY target were to look for the problem .
There really is not much more help I can suggest other then look for a better service shop in the future .

ASE