2007 Citroen C1 High Idel Lambda

PPDoyle

Hi guys and Girls , i got my car serviced this month it required a new centre exhaust, which i had done, 2 years ago i replaced the cat when it went faulty, at that time i put new plugs in so this year i didnt bother doing the plugs but did do filters and oil. and went for NCT sadly it failed

low idel .......Co 0.1 Vol%.......above 30%................. PASS

840 (rpm)....HC 10ppm ......Above 0 ppm........................N/A

High Idel......Lamda 1.11....Not between 0.97 and 1.3..... MAJOR

2660 (rpm)..CO 0.02 vol%.............above 0.20%.........PASS

HC 9ppm ........ ........above 200ppm........................PASS

so i changed the plugs, added an petrol additive for emmisions and cleaned the PCV valve which was manky and had it retested , and it failed again again with the High idel Lambda, which changed to

High Idel......Lamda 1.12....Not between 0.97 and 1.3..... MAJOR

i am not showing any engine light on the dashboard and i dont know what to check now , any ideas ? i do have a spurious pre cat sensor for the car that i never used, i got it when the Cat acted up i dont have a post cat sensor , or maybe it could be that the new center exhaust i had put in isnt tight enough but i have no way to pump air into the system to see if their is a leak around it , and if it helps i have a car diagnostics ocb device that says it can look at emmisions readings from the onboard computer a quick look shows readings for bank one and 2 , but i dont understand them , i could put them up if that helps , any ideas would help thanks

peter

mk7r

You need to look at the pre cat lambda readings and the fuel trims, if they are in spec then you have a leak in the exhaust somewhere after the first 02 sensor. If they are not in spec then you need to figure out why (sensor itself, map sensor, intake leak etc)

PPDoyle

thanks for your reply, i had a look at the sensor with an OBD11 tester and although i dont understand the results maybe someone here does ?. this test was done with car ticking over

......Bank 1 Sensor 1........

rich to lean sensor treshold voltage constant....... test value 0.445v

lean to rich sensor treshold voltage constant....... test value 0.445v

.......................minimum sensor voltage for test cycle calculated...............

Test value 0.000v

minimum limit 0.005v

maximum limit 0.400v

.......................maximum sensor voltage for test cycle calculated...............

test value 0.905v

minimum limit 0.500v

maximum limit 1.045v

........................Time between sensor transition calculated...............

test value 0.280s

minimum limit 0.000s

maximum limit 3.000s

.......................................Bank 1 Sensor 2...................................

rich to lean sensor treshold voltage constant....... test value 0.600v

lean to rich sensor treshold voltage constant....... test value 0.600v

.......................minimum sensor voltage for test cycle calculated...............

Test value 0.000v

minimum limit 0.005v

maximum limit 0.400v

.......................maximum sensor voltage for test cycle calculated...............

test value 0.850v

minimum limit 0.500v

maximum limit 1.045v

i did have a look at the sensors while in live view looking at the graph moving and the test was done in 4 single steps

1. 02s B1 S1
2. 02s B1 S1 STF
3. 02s B1 S2
4. 02a B1 S2 STF
5. and although applying 3000 Revs during each test caused the graph to change and reduce again test 4. did not move in any way and showed a flat line both before and after revs were applied maybe someone knows if this is right or not?

PPDoyle

pictures added below

as said above the 02S B1,S2 STF readings on screen in live view never changed even when i reved up to 3000RPM