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Ask Mike Kelly Your Own Question
Mike Kelly
Mike Kelly, Auto Service Technician
Category: Car
Satisfied Customers: 5470
Experience:  17 years experience as an auto mechanic, foreign and domestic. 5 years running my own repair business.
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my vauxhall corsa 1.0 12v 1999 failed mot due to high co2 readings

Customer Question

my vauxhall corsa 1.0 12v 1999 failed mot due to high co2 readings also car running ruff on low revs how do i rectify this
Submitted: 4 years ago.
Category: Car
Expert:  Mike Kelly replied 4 years ago.
Hi,my name is mike and I will assist you with your question.
The high readings combined with the running rough is consistent with a failing mass air flow sensor. The mass air flow sensor is responsible for measuring the fuel air mixture and when failing results in these symptoms.
Customer: replied 4 years ago.

have put on new mass air filter on but has made no difference

Expert:  Mike Kelly replied 4 years ago.
Ok if you have put on a new exhaust complete with new o2 sensors and the mass air flow has been changed,the only thing left that will cause the high reading is improper communication with the ECU to the vehicle. This likely does not mean that the ECU has to be replaced but means it needs to be reset or updated.