on March 9, 2013, 5:11 pm, in reply to "Re: Citroen Xsara 1.4 2000 - High emissions, code 42 o2 sensor circuit #"
In my humble opinion
Your emission readings are quite typical of a failed CAT apart from
The CO readings 0.98/1.00, I would say are a little too high. I would expect to see around 0.60-0.70 if the vehicle was running correctly but the CAT had failed.
Hopefully someone will correct me if I am wrong with the above statement.
So you may have a failed CAT but due to another reason.
Addressing the fault code
As mentioned above check the heater circuit...
continuity test
is the ecu turning the heater on?
is there power to the heater circuit?
Check current flow through the circuit
You may have to load test all the o2 circuits
Has this got an after cat o2 sensor?
If so
Can you graph both sensors during a road test to check the efficiency of the CAT? or even just to eliminate the CAT from your enquiries.
HTH
James
