OFF-ROAD USE Enhanced Exhaust Header

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Mini Mania, Inc. Service Bulletin

Subject: Header CAT & EML light.

Issue

While the off-road use type exhaust header & integral high flow catalytic converter provides excellent performance, some customers have experienced the EML light being triggered after some period of operation. Typical of this occurrence is for the EML light to trigger again within a period of days to weeks after resetting the computer. The underlying OBD II code is P1420, indicating low catalyst efficiency has been detected.

This condition is often a normal occurrence with a high flow catalytic converter, and does not necessarily indicate a catalytic converter failure.

This is an acceptable operating condition for an off-road use header such as the NME1004, NME1104 & NME9004 units.

Cause

This high performance header is equipped with a low backpressure, high-flow catalytic converter, which contributes substantially to its high level of performance. Even though emissions are within acceptable parameters, the secondary O² sensor is seeing different operating conditions than originally intended by the car’s designers. Because the output of the sensor is different than expected, the ECU concludes that there is a problem with the catalytic converter.

Testing has concluded that while the EML light may be triggered, the catalytic converter is functioning normally.

Testing

A qualified technician observing proper safety procedures should perform testing.

With the car safely on a lift, separate the CAT back exhaust system from the header at the flange. With aid of a flashlight, perform a visual inspection to verify the catalytic element is intact and complete. Reassemble.

Using a 4 or 5 gas exhaust analyzer, verify that tailpipe emissions are within specifications.

With ECU diagnostic equipment (such as the ) check fuel trims to verify proper ECU control of the engine operating parameters.

Verify the problem is not cause by a defective O² sensor. A defective sensor can cause this symptom and may damage the vehicle if left undiagnosed.

In the event of catalyst failure, a replacement unit may be available. Contact Mini Mania for price and availability.

Remedy

Several courses of action are available in the case of EML lamp illumination as described above:

1. Continue operating the vehicle normally. In this case, be sure to check OBD II codes periodically with an appropriate code reader (NME4020 or similar).
2. Install an O² sensor simulator device to extinguish the EML lamp. In this case, be sure to periodically check exhaust gas emissions to verify proper catalyst operation. Like the NME1104 & NME9004 header O² sensor simulator devices are designated for non-highway off-road  use.
3. In some cases an O² sensor restrictor device (such as our NMK9009) will resolve the false indication. Contact Mini Mania for details about this item. 
4. Reinstall the original stock manifold with integral catalytic converter & reset computer.

Warranty Considerations:

Warranty covers header materials and workmanship. Heat discoloration of the stainless steel tubing is considered normal (not a materials or workmanship related issue) and is not covered by warranty. Catalytic converters sold for off road use are frequently operated in highly tuned vehicles. They are subject to extreme operating conditions when subjected to track driving conditions, and are not covered by warranty. Melted catalytic elements are symptomatic of this case. Due consideration should be given to use of a straight through header, not equipped with a catalytic element.

Article Date: Apr 20, 2004
Car Accociations: NEW_MINI
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