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ABS and VDC Lights

Good morning!!

I have a 2002 Legacy Outback 6Cyl with VDC. Over the weekend my dash lights for both the ABS and the VDC will not go out after the normal starting of the car. Does this mean I have a brake problem?

~~John S.

It is hard to tell from afar, but I think that you do probably have a problem in the ABS system.

Subaru’s VDC system (like the similar VSC system of other manufacturers) does two things essentially–it reduces engine power and/or applies braking force to one or more wheels if it senses that a skid is taking place. Since your ABS system has to be working perfectly in order for the VDC system to function, it is very likely that there is an ABS-related problem. This is unlikely to produce braking problems under normal conditions, but–of course–not having ABS could be problematic in wet or icy road conditions, so you should have this checked by either an independent Subaru specialist or a Subaru dealer.

You did not tell us that the Check Engine Light (CEL) is lit up, but, then again, that detail is frequently omitted by people posting questions. If the CEL is illuminated, then there is another possibility. Since the VDC system also requires that the engine is operating at its optimum, if the car’s OBD system detects a misfire or an emissions-related problem, the VDC system is automatically shut down.

Just as an example, many years ago, a bad purge valve in my '02 Outback’s Evaporative Emissions System led to an illuminated CEL and simultaneously, an illuminated “VDC off” light. Luckily, this was covered under warranty and I was back on the road in about 30 minutes, with all warning lights extinguished.

Is your CEL lit up?

Yes sir my CEL is on and has been for some time. I was told it was exhaust oriented and was not that big a deal. My car has 177,000 miles on it.


Why people frequently omit the vital detail of the CEL is something that I just can’t seem to fathom.
Apparently, some folks seem to think that it is in the normal scheme of things for a CEL to be lit up most of the time, but that is only true if a car is poorly maintained or if mechanical issues are ignored.

Even if the original “no big deal” exhaust problem is still there, by now there could be a long list of stored trouble codes, simply because one ignored problem frequently leads to a cascading series of problems. Once the CEL is lit up, you have no idea of how many new problems may have developed, and as a result it is not wise to ignore that light.

That being said, I suggest that you bring the car to a competent mechanic in order to bring the car up to date by replacing things like spark plugs, plug wires, air filter, and fuel filter, and that you have the mechanical issue(s)–very possibly an 02 sensor or two on the exhaust system, or a leak in the exhaust system–taken car of.

More than likely, the CEL will extinguish itself once the car is properly maintained and the “no big deal” exhaust issue is taken care of. Even if the CEL does not turn itself off at that point, at least diagnosis of the remaining problem will be that much easier.

Fix your CEL first and the ABS and VDC light likely will go out. They do go on related to a CEL.

Leaving your CEL on for prolonged periods can lead to very expensive damage to the emissions equipment like your O2 sensors and other parts.

Get a decent mechanic who knows Subaru. Yours is a bit harder with the very rare H-6.