pistons
06-07-2009, 11:07 AM
:mad: I am one fed up Skoda owner (Fabia ’03, 1.4l, 16v).
The EPC warning light has been triggering fairly regularly for the past year+. This begun whilst the car was still under warrentee but the Skoda garage said that no fault code had been written to the logs so they could not help. I find this strange, since having since bought a Ross-Tech and a Gendan "Engine Check Pro" reader, a P0106 code is always written to the log after the EPC light has triggered.
The fault seems to occur most often whilst negotiating small local roundabouts, usually just as pulling away from them. It has also occured whilst pulling out to overtake!!! - I rarely do that now in this car - I don't trust it!!
The EPC light has come on many times but twice it has come on and the EMU immediately switched into the dreaded limp home (LH) mode. Oddly, the LH mode could be cleared if the wiring plug on the throttle body was disconnected and reconnected (with the engine off). At first I thought this may be due to a poor contact etc but it all checked out OK with a DVM.
Pulling the plug is not the ideal quick fix but this was the only way I could get out of LH mode and get home and then attempt a proper fix.
I also started examining simply everything and replacing the various parts and sensors that may be causing the P0106 code.
I found a crack in the tube between the throttle body and the brake servo. This would effect the manifold pressure so I replaced the tube – better brakes but the P0106 error continued to reoccur.
I measured the cylinder pressures in case there was a burnt valve creating some back pressure – no signs of that.
I replaced the force (MAP) sensor on the inlet manifold as this is the sensor reads the manifold pressure. – P0106 error still reocurred.
I measured the manifold pressure, using the EngineCheckPro software, with the engine idling, accelerating and decelerating etc. before and after the force sensor was replaced. The range of readings obtained was the same before and after. All readings seemed reasonable and credible. The P0106 fault code continued to reoccur.
I replaced the brake switch above the brake pedal as suggested on the Skoda Fabia forums. Reports suggest that this part often fails and, since it is part of the EPC logic, could cause this problem – despite replacing it the P0106 error still reoccurs.
Note: Dismantled the old brake switch and found it to have been OK and probably not at fault.
I have taken the inlet manifold off and examined if for damage. All seems OK
I have cleaned out the throttle body. A bit dirty but cleaning it did not change anything.
I have used Ross-Tech to reset the throttle position sensor. Does not cure the fault.
I have checked the fuel pressure on the delivery rail – all OK.
During the many many months of bother the only code that ever gets repeatedly logged is P0106 signifying a “Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem”. There was a single occurrence of a P0170 and a P0106 occurring together but as a cell in the battery failed at that time I don’t know if this was areal problem or an simply another fault which I then cleared by replacing the battery. The P0170 code has not recurred since the battery was replaced..
On perhaps a third of the occasions when the EPC light shows the TSR light mometarily come
on as well but no extra codes are recorded, only P0106. From what I have read, the TSR light comes on if the TSR unit fails and this will cause that light to stay on. It is also said to show but clear itself if the battery voltage falls too low. This then clears if the engine is restarted.
Two pieces in this control circuit which I have not yet replaced are the throttle body and the accelerator pedal position sensors. Having already spent about £300 on parts (to no effect) I am reluctant to spend a further £160+ to replace the throttle body without some hope that this may be needed. Each of these parts seem to have fault codes of their own. Since I have not yet seen faults in the range P0120 et seq, P0221 et seq or P1171/1172 I am reluctant to replace these actuators/sensors.
From what I read on the forums this type of EPC problem is not uncommon, with many owners and garages struggling to solve this. Why cannot the EMU give a better hint about what is wrong. Despite the fault readings that I see all I am left with is questions and no solution.
Is failure of the throttle body likely? I am puzzled as to why unplugging the wiring to the throttle body can snap the car out of the LH mode. I have used a DVM to look for a poor contact etc. but cannot see a fault. In any event I have never seen any of the error codes which I would expect to see from a malfunction in the “drive by wire” parts between the throttle pedal and the throttle body. Surely, if the throttle body etc was defective, wouldn’t this produce some codes other than P0106.
:aargh4:PS. The habit of switching to the Limp Home Mode instantly without warning has proved to be extremely dangerous. This problem first occurred, without warning, whilst overtaking, but fortunately I was not on a motorway! Surely there must be some other way to warn the driver of the fault and to allow sufficient time for the car to be brought to a safe halt in a safe place. The instant loss of power and the rapid deceleration that follows could easily leave one stranded in the fast lane of a motorway with nowhere to go apart from the mortuary. At the moment I dare not go on motorways with this car. I consider this to be a very serious safety issue.
The EPC warning light has been triggering fairly regularly for the past year+. This begun whilst the car was still under warrentee but the Skoda garage said that no fault code had been written to the logs so they could not help. I find this strange, since having since bought a Ross-Tech and a Gendan "Engine Check Pro" reader, a P0106 code is always written to the log after the EPC light has triggered.
The fault seems to occur most often whilst negotiating small local roundabouts, usually just as pulling away from them. It has also occured whilst pulling out to overtake!!! - I rarely do that now in this car - I don't trust it!!
The EPC light has come on many times but twice it has come on and the EMU immediately switched into the dreaded limp home (LH) mode. Oddly, the LH mode could be cleared if the wiring plug on the throttle body was disconnected and reconnected (with the engine off). At first I thought this may be due to a poor contact etc but it all checked out OK with a DVM.
Pulling the plug is not the ideal quick fix but this was the only way I could get out of LH mode and get home and then attempt a proper fix.
I also started examining simply everything and replacing the various parts and sensors that may be causing the P0106 code.
I found a crack in the tube between the throttle body and the brake servo. This would effect the manifold pressure so I replaced the tube – better brakes but the P0106 error continued to reoccur.
I measured the cylinder pressures in case there was a burnt valve creating some back pressure – no signs of that.
I replaced the force (MAP) sensor on the inlet manifold as this is the sensor reads the manifold pressure. – P0106 error still reocurred.
I measured the manifold pressure, using the EngineCheckPro software, with the engine idling, accelerating and decelerating etc. before and after the force sensor was replaced. The range of readings obtained was the same before and after. All readings seemed reasonable and credible. The P0106 fault code continued to reoccur.
I replaced the brake switch above the brake pedal as suggested on the Skoda Fabia forums. Reports suggest that this part often fails and, since it is part of the EPC logic, could cause this problem – despite replacing it the P0106 error still reoccurs.
Note: Dismantled the old brake switch and found it to have been OK and probably not at fault.
I have taken the inlet manifold off and examined if for damage. All seems OK
I have cleaned out the throttle body. A bit dirty but cleaning it did not change anything.
I have used Ross-Tech to reset the throttle position sensor. Does not cure the fault.
I have checked the fuel pressure on the delivery rail – all OK.
During the many many months of bother the only code that ever gets repeatedly logged is P0106 signifying a “Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem”. There was a single occurrence of a P0170 and a P0106 occurring together but as a cell in the battery failed at that time I don’t know if this was areal problem or an simply another fault which I then cleared by replacing the battery. The P0170 code has not recurred since the battery was replaced..
On perhaps a third of the occasions when the EPC light shows the TSR light mometarily come
on as well but no extra codes are recorded, only P0106. From what I have read, the TSR light comes on if the TSR unit fails and this will cause that light to stay on. It is also said to show but clear itself if the battery voltage falls too low. This then clears if the engine is restarted.
Two pieces in this control circuit which I have not yet replaced are the throttle body and the accelerator pedal position sensors. Having already spent about £300 on parts (to no effect) I am reluctant to spend a further £160+ to replace the throttle body without some hope that this may be needed. Each of these parts seem to have fault codes of their own. Since I have not yet seen faults in the range P0120 et seq, P0221 et seq or P1171/1172 I am reluctant to replace these actuators/sensors.
From what I read on the forums this type of EPC problem is not uncommon, with many owners and garages struggling to solve this. Why cannot the EMU give a better hint about what is wrong. Despite the fault readings that I see all I am left with is questions and no solution.
Is failure of the throttle body likely? I am puzzled as to why unplugging the wiring to the throttle body can snap the car out of the LH mode. I have used a DVM to look for a poor contact etc. but cannot see a fault. In any event I have never seen any of the error codes which I would expect to see from a malfunction in the “drive by wire” parts between the throttle pedal and the throttle body. Surely, if the throttle body etc was defective, wouldn’t this produce some codes other than P0106.
:aargh4:PS. The habit of switching to the Limp Home Mode instantly without warning has proved to be extremely dangerous. This problem first occurred, without warning, whilst overtaking, but fortunately I was not on a motorway! Surely there must be some other way to warn the driver of the fault and to allow sufficient time for the car to be brought to a safe halt in a safe place. The instant loss of power and the rapid deceleration that follows could easily leave one stranded in the fast lane of a motorway with nowhere to go apart from the mortuary. At the moment I dare not go on motorways with this car. I consider this to be a very serious safety issue.