VersaTune User Forum

I have a 2007 Mazda cx-7
I've installed LED brake lights , and now at night or when lights on cruise control is disabled by DTC P0571 and P0703.
I've disabled those DTCs, and now scanner shows no active DTCs, but disabling didn't affected cruise control behaviour, it is still disabled when lights on.

Does "disable DTC" function affects only DTC reporting part of self check , and if it is , does this mean that other checks like EGR or any other that (may) matters to performance are just muted but still influencing performance calculations ?

Disabling the DTCs when flashing the tune only inhibits the engine light or any other light to come on when the ECU software detects those faults. Disabling them will not change the way the ECU logic will react when such a fault is detected.

You should got o a Mazda dealer and have this problem checked and fixed from their IDS. You could also try to change the behaviour of the CC using a 3rd party tool such as ForScan.

My issue with CC can't be fixed by IDS/ForScan , because it's caused by hardware modification, not by mailfunction.

Basicly in case when we have modification which matters to ECU calculation logic , disabling DTC won't disable detection of "faulty condition" (from ECU point) and therefore ECU will use "safe calculations" affecting performance. It's doesn't matter much in case of CC , but in case of EGR or O2 sensor it is matters !

In the case of the secondary O2 sensor the ECU logic will not change, it's only an alarm that the emissions are not how they are supposed to be.
As for the EGR the ECU logic will not change that much either. Nor in case of the CC. You will not have different fuelling maps, ignition values, or whatever, because CC doesn't work. That DTC disable function is only for those cases when the owner is aware of the problem, knows it's not something that can affect his safety or engine (or if it's the case then he simply chooses to ignore it). It's not for fixing the actual problem.

So the DTC disable feature works exactly as designed in VT, and it works in exactly the same way in the Mazda IDS software or other management tools.

Did you ever drove a car with broken 2nd O2 sensor ? I suppose you didn't, because it is MUCH difference. There is HUGE power loss in this case. Not just a "warning light"

A broken O2 sensor will affect the idle AFR and sometimes the cruising AFRs. You can pull the secondary O2 sensor connector and the AFRs will look good again. But in both cases you will have the engine light on which if you disable for that DTC the car will work perfectly.

P.S.: yes, I did

Can you comfirm on what the DTC disable actually does ?

I have an OBD display as a monitoring to the car always on (instead of GPS) with some additional important information that reads error codes etc.
Does it only stops the engine malfunction light come on, or is it also disabling checking of these items altogether. ie if I remove the rear O2 sensor, and disable all codes connected to it. so the ECU doesn't even check if there is one, and no codes reported to OBD port / MIL ?

I know these switches are in the hex file of any ecu, I am wondering if they are disabled in hex if chosen in the customization and DTC disabled.

Walle wrote: ↑August 29th, 2021, 8:29 pm I have an OBD display as a monitoring to the car always on (instead of GPS) with some additional important information that reads error codes etc.
Does it only stops the engine malfunction light come on, or is it also disabling checking of these items altogether. ie if I remove the rear O2 sensor, and disable all codes connected to it. so the ECU doesn't even check if there is one, and no codes reported to OBD port / MIL ?

Disabling a DTC will only inhibit the check engine light when triggered by that PID. The PID values will still be available for reading.

Why is this not implemented like in Mazda Edit whre a PID check can be completely disabled? (To prevent safe mod etc if "cryptical components are removed.

Because Mazdaedit is a different software.
However you can adjust your tune so that it will react differently on the "new" values of that PID.
What PID are we talking exactly here and what issues do you actually have?