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Om651 exhaust back pressure sensor p047128 2bar out of rang after shutting engine off
Problem: EML, late gear changes, jerking, no power. Realised my plug had unplugged itself from the sensor. But after refitting there was still a problem.
Ok so i fitted a new exhaust back pressure sensor (EBPS) but the engine is still throwing this fault p047128. If i drive it after clearing the fault the sensor readings are perfect and car is back to 100% but when the engine is turned off, after exactly 1minute the EBPS jumps to 2bar and the fault returns and car is back to limpmode. I have tried 3 sensors including original..all doing the same thing. All dpf readings and pressures are fine, car drives perfect until the car is turned off .
I Tried fo find info all over the net about this but no answers!
So just for your info, the sensor has a small pinhole which pushes air out into the plug (yea the plug connector! which also has vent hole). This then gives a reading.
FIX: pull back the connector from sensor a tiny bit whilst its plugged in. do not push it down as far as it goes because there needs to be a gap between the 2 tiny holes (one on the sensor and one on the plug that measures the pressure reading). I used some silicone spray on the rubber watertight seal of the plug to make the plug side on easily otherwise it needs a tight push which ends up being pushed down too far. Best way to do it it push it until you feel a clip then pul back on the plug. If you have live data, turn the car off and watch it. If the pressure stays at about 1.01-1.1bar then your problem is sorted. If it jumps to 2.0bar you need to fiddle with the plug
So with the sensor unplugged whilst the car was on, it was showing 2 bar. so what was happening was when the engine was switched off after exactly 1minute, the sensor was acting like it wasn't getting a flow of gasses and this was because the gap between the vent on the plug and the pinhole on the sensor was way too small to measure a reading. Problems now fixed.all back to normal with a new febi 171266, nothing was wrong with my old sensor but at 182K miles i changed it anyway. Good luck guys
Last edited by king786khan; Dec 14, 2024 at 05:36 PM.
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