DTCS in vehicle

okay so theres a thing where you can hold the read button and tap the rear fog light switch three times ... then it tells you "checking dtcs" etc can anyone state exactly what this sequence should say when all is well? so maybe someone here that doesnt have any dtc's set right about now could pop outside and run through the read + tap fog x 3 thing and let me know what they get reason being is that i have an intermitent (essr) fault, so i bought an obd2 scanner/resetter, went through the routine, it showed up no fault (maybe not surprising as at the time i tried to read/reset codes was one of the periods where the fault wasnt even showing up on the check engine light), so i checked the read + fog tap, and it just states the same as when the car showed a problem

It will say " NO DTC SET " if you have no codes ...

marvic18 .. yeah see mine is the same ... checking dtcs dtcs in vehicle abs dtc set uem dtc set cem dtc set (amongst other "checking" and" ready") ...and so on... not being awkward but are you sure that is correct Clan? so if we interpret "abs/uem/cem dtc set" as that my abs/uem/cem has faults, why do i get no codes when i scan the obd2 and how come volvo themselves didnt tell me i had something wrong when i took it in earlier this year for other work ... after all it stated the same sequence before and after they played around with it

Where it says DTC set it means there are codes in the relavent module , CHECKING means it is waiting for fault codes to be logged , could be a very long time ! . If NO systems have fault codes it will say NO DTCS SET ... I Guess your non volvo code reader is incompatible and that they didnt clear the codes after they had finished reading them , if in fact they did read them .. when the car is in for service it should leave with no fault codes in the system unless there are faults needing attention which are aparant after the codes were cleared on the service ..

well ... its a long story ... but ill try and shorten it it goes a little something like this 1. car shows essr 2. acceleration is extremely hesitant (but will still take me up to 100+) 3. few days pass (possibly 3-4 restarts of the engine) 4. essr disappears along with acceleration problem 5. 1-2 days pass, then back to square one again volvo had it in for 2 weeks reading codes, changing accelerator sensor, cleaning TB, ugrading software and finally decided on replacing the ECM, all of which wasn't cheap ... I would of expected that after 2 weeks almost solid tinkering they would have pretty much covered all bases, but sure enough its back again (have posted about this before and people suggested an emmissions problem, so I bought the obd2 in theory that if was, then I would know exactly what and fix it) I understand that volvo wouldnt use something they have bought off of ebay to read/clear codes ;) but thats precisely the reason they wouldnt have missed a problem surely? ... and if I'm paying them to fix my car then I'm also paying them to erase codes properly, but anyway I'm going off the point its not that I'm bothered that there are codes stored, its just the sinking feeling I get whenever I start the engine close my eyes and hope that it doesn't tell me "essr" and lose acceleration, just want to get closer to the problem

Some questions: Have you tried an OBDII scan when the ESSR message is displayed? Does the MIL (check engine) lamp ever light? Have you tried reading OBDII pending codes?

Chris, 1. i only bought the scanner the other day ... the car has started behaving itself since(not displaying the essr), but it will come back most likely today, and i will read obd again and post as soon as it happens 2.check engine light comes on with the essr, stays aslong as i have the essr and then disappears along with the essr (note that acceleration sometimes returns to normal with cel/essr still on, but the fact that its still shows may just be residual?) 3.pending? ... im guessing you mean old codes?, the scanner is only basic and shows no codes whatsoever

Pending codes are ones that have been logged but not been there long enough to set the MIL lamp. So it it is worth a look to see if any are logged when you have the sort of problem you are experiencing. Does your scanner have this function? If you get a code set it is also worth noting the freeze frame data.