Does your ABS also come on when the check engine does. If it does probably the OVP. If not chances are the O2 sensor is on it way to retirement.
Hope this helps.
m

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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)