Generations

Engine Codes

Engine code	MY	Model	ECU	Notes
APB	1998-2001	North American S4	see below
ASJ	2000?	RS4	F-box
AZR	2001?-2003		Q/K-box
AGB	1997-2001?	European S4	C/D-box	No post cat O2 sensors, Bosch MAF, original intake manifold
AZB	2001?		G/N/P-box
APB	?-2002	Allroad/A6	X/L-box
BEL	2003-?		R/MX/S/T-box

OEM equipment

MY	Badge	ECU	Build Date	MAF	BPVs	ESP	Transmission	F-hose	Notes
1997-1999		C-Box	09/97-08/99	Bosch	710	no	6-speed	yes	AGB engine code. Not available in North America. Flush door handles. Early door mirrors. Thin door trim. Analog clock in dash. No plenum chamber cover. Reversed battery terminals. Face down spare.
2000		A-Box	09/99-05/00						Possibly Al uprights, interchangable with ESP/Hitachi equipped cars but requires engine recode and a Bosch MAF
		B-Box			710A		Tiptronic	no	Possibly Al uprights, interchangable with ESP/Hitachi equipped cars but requires engine recode and a Bosch MAF
2001		H-Box	06/00-09/00	Hitachi	710A	yes	6-speed	yes	Steel uprights, introduction of ESP, interchangable with M-Box but requires cluster recode
		J-Box					Tiptronic	no	Steel uprights, interchangable with L-Box
2001.5		L-Box	09/00-05/01		710B				Revised TBB, updated intake manifold, sport package (w/Al mirrors) avail, Avant avail
		M-Box					6-speed, updated synchros/sliders
2002		T-Box	06/01-07/01						Interchangable with M-Box
		AA-Box					Tiptronic		Interchangable with L-Box

• Note: The build date cutoff for 2001 to 2001.5 is inconsistent and sometimes arbitrary. Both '01 and '01.5 cars have been reported as 09/00 build.
• Note: Manufacturer Year is inconsistent and sometimes arbitrary. See Notes below.
• Note: It is a common misconception that 2001.5 introduced updated oil lines. There is no conclusive evidence of this.

North American Production numbers[1]

MY	Sedan	Avant	total
2000	5647	25	5672
2001	4770	1228	5998
2002	642	198	840
Total	12,096	1451	13,547

2002 is build date of 06/01 to 07/01

Notes

• http://forums.audiworld.com/s4/msgs/802094.phtml
• poll here: http://forums.audiworld.com/s4/msgs/2447926.phtml
• There is some confusion with cars near the 5/00 build mark (none verified)
  1. Some 2001 cars came with Bosch MAFs (and presumably A-Box ECUs).
• There is some confusion with cars near the 09/00 build mark (none verified)
  1. Some are 2001, some are 2001.5
  2. Some 2001.5 came with H-boxes and do not appear to have F-hoses
  3. Some 2001.5 are reported to have mismatching wheel/trunk badges
• Andy Whittaker's UK 1999 S4 seems to have a C box as too does Nilesh "Ram" Ramrattan's MTM Stage IV car (also UK spec).
• The L and AA box information may be incorrect. Please mail me or post a comment in the talk section.
• If the OEM equipment on your car does not fit into this table and you are the original owner, please post a comment in the talk section.
• If the OEM equipment on your car does not fit into this table and you are not the original owner, it is highly likely that some of the parts have been swapped out.