OBDII Scanner: Or How To Save A Lot Of Money On Car Maintenance

Once again, this little device to the left has saved me $100+.

A few years ago, my Chevy Volt’s ABS warning light came on. A brief search around various forums said the most likely cause was driving through deep puddles in wet weather. That the water would muck up the ABS (automatic braking / skid avoidance sensor) and, typically, waiting until everything dried out and then resetting the trouble code would fix it (would make the warning light go out).

To reset the trouble code requires an OBDII scanner of some sort. OBDII is the on board diagnostics system and a standard connector for interacting with the system has been mandated on all new cars in the US since 1996 (but the original OBD systems date all the way back to 1969!).

When you take your car to the shop and they come back after 15-20 minutes with a printed report of various trouble codes? Most likely, a standard report produced by the OBDII system.

There are three types of codes, more or less, confirmed, pending, and permanent. Confirmed and pending are typically the “detected a problem, might go away” and “might be a problem variety”. Permanent are the “yeah, really, a problem was detected” variety. Would have been at least $150 to clear the codes at a dealer and, of course, an upsell for many hundrends of dollars to “fix” the “clearly on the verge of failing” sensor.

Yesteday, my Volt barfed up a “service high-voltage charging system” message and refused to charge the batteries. Plugging in the OBDII scanner, it showed a few error codes across all varieties. Specifically, it was claiming low coolant. But there was plenty of coolant in the battery coolant tank.

Clear the codes!

I cleared all the pending and confirmed trouble codes. Permanent codes can’t be cleared but they will also update automatically based on new sensor data.

The car has to be turned on to do this. And, because the battery was dead, the gas engine was running.

Within seconds of clearing the codes, I heard the engine rev a bit, indicating that it was charging the batteries!

Plugging the car in and it immediately started chargin.

So, once again, the OBDII scanner saved me at least $150 and a lot of inconvenience just to clear a code. An unscrupulous mechanic would have printed out the report, showed it to me, and charged $800-$1200 to replace the charging sensor wiring harness.

I highly recommend adding one to your toolkit. There are a bunch out there. The BlueDriver isn’t the cheapest, but it works over bluetooth and looks up trouble codes on the internet to provide a list of the most common fixes to any given trouble code. Not the “dealer recommends you spend $#,### replacing this thing” fixes, but fixes looked up in various online car enthusiast forums that are a treasure trove of tips and tricks!


Of course, the concern is whether clearing the codes might cover a problem.

It really won’t. Any important– about-to-cause-destruction– sort of code is of the permanent nature. It can’t be cleared and it will be updated.

The confirmed/pending codes are much more advisory. They may indicate very real problems– certainly, the ABS sensor was mucked up by water and the coolant sensor did detect low coolant because of sloshing– but if there is a real problem, then the cleared codes will just pop right back up in short order anyway.

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