I've had my engine light on since November last year around the time I was leaving a car park and went over a little bump that seemed to knock something out of place. Few days later my Engine Management Light came on and started to give a rough idle. I started investigating and plugged in my basic OBD scanner, I was given the following codes;
P0172 - Engine running Rich
P0130 - 02 sensor circuit Bank 1 sensor 1 issue
My first instant thought was replace the 02 Sensor, which I did, I also cleared the code and seemed to work fine for 15-20 minutes then boom rough idle starts again and then Engine Light comes on, and the rough idle stops but the drive feels different more rough/throaty and I can tell there is more Fuel being consumed. I then changed the Mass Air Flow sensor and cleaned out the throttle body for good measure but again no luck. I also changed the fuel filter and also the fuel injector seals.
Finally giving up on the DIY, I took the car to a "VW Specialist Garage" who advised me me they cannot find any vacuum leaks and that there may be a leak somewhere deep within the intake manifold, they wanted £250 to just check the intake manifold, so I went online and ordered a new one 2nd hand very good condition. Replaced the seals and fitted this myself. Still no luck. I've been to an Automotive electrician to see if there is potentially something up with the 02 Sensor wiring loom but they said they cannot find any faults and charged me nothing. In total I've taken this car to 4 garages "well reputed garages" but no one can find the roots cause. One garage did point out that the Flex hose was cracked so I had that replaced by them.
-MAF sensor changed
-02 Sensor changed (certified brand new BOSCH sensor)
-Intake Manifold and Seals replaced
-Fuel Injector seals replaced
-Fuel Filter replaced
-Flex Hose Exhaust pipe replaced
-No air leaks detected by garages
-No one can find out what on earth is going on.
My car is almost 20 years old, I've had it for almost 4 years and take good care of it since I've had it (oil and filters replaced every 6 months). I'm not ready to depart with it as its ULEZ compliant and very economical (post EML issue).
Vehicle: VW POLO 9N Twist 1.2 Petrol 2004 - Manual
Engine Code: AQZ
Mileage: 60,000 miles
Please someone help I am at my wits end
