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Hi all,

I'm running 100 cel cats and I keep getting the check engine light coming on which is obviously due to the high performance cats. By memory I think the error codes where PO420 & PO430.

I believe there is a way to over come this problem, so can anyone advise me what I need to do or purchase to stop the error code.

My car is a 2002 V8



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Hi Will,

I know the race ecu codes just check that the post cat sensors exist but ignore their readings. This is a fix of sorts but not necessarily the cheap one I expect you were hoping for.



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This doesn't answer directly your question but here's the code definition. 420=Bank 1, 430=Bank 2.


Definition type Definition

GENERIC Catalyst System Efficiency Below Threshold (Bank 1)

A 'Generic' definition (if shown) is a standard definition for this code that applies for all manufacturers.

Perhaps this thread is useful?;#entry237794


Edited by CharlieC
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No CEL problems with 100cpi cats and the standard high-torque S350 code, but I was under the impression that the emissions might be borderline.


Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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It would seem that your ECU is reading the post cat O2 sensors and determining that the CAT's are not doing their job completly (i.e effiecently) as determined by the the oxygen content. So (1) it would seem you have a USA destined ECU and (2)the 100 cell CAT's aren't doing the job completly. There is a spark plug spacer that the rice grinder boys use to space the sensor further away to mask the richer gas content when placed in the pre cat O2 sensor position, I don't think it would help in this case, but for a small investment you could try it? If you determined to keep the CATs there's also a little electronic device (a fooler, 555 timer chip) which is also used in the pre cat O2 sensor position, which might also fool the post cat reading to the ECU.


The Older I get the Faster I was

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