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Code in Layman's terms


Would someone be able to explain the OBD II code DTC 03 in Layman’s terms?


There’s no such thing as an OBDII code 03.

OBDII codes start with a P

For example, An OBDII code P0303 would indicate a misfire in cylinder #3.


OBD II = On Board Diagnostics version 2, Used on 1996 and later cars and trucks

DTC = Diagnostic trouble code, the output from OBD II.

DTC 03 is Filtered Battery Voltage Out of Range. This means that the battery voltage is out of range. Typically low voltage. The filtered part is to remove the spikes from the analysis to get a better reading. Likely a bad battery or a bad battery cable.

Unless it’s a body code, which starts with a “B”.
Or a chassis code, which starts with a C.

But they’re all a category alpha designator plus four numbers.
Give us the entire code along with a brief description of the symptoms and the year of the Sunfire and perhaps we can help.

Where did you get the code and were you told what it was for.

DTC 03 is a GM specific code. Since this is a Sunfire, likely and old one, that means its “Filtered Battery Voltage Out of Range” Battery voltage over 16.5 volts or below 9.0 volts

Can’t be that old. The Sunfire wasn’t introduced until 1995. It was sold until 2007.
OBDII was mandated starting with the 1996 model year.

If I read the Chilton manual correctly, it shows an 03 code to be MAP problem. These are the codes for 1994-1995 cars…so it says. If true that’s good, other than that I find Chilton manuals useless.

If this is a 94-95 GM vehicle, it may have the bastardized non-compliant OBDII.

This means you can’t pull codes by jumping between the A and B terminals on the ALDL connector to get the Check Engine to flash, and a standard OBDII code reader won’t communicate.

You need at least a TECH II GM scan tool to pull codes from this generation of GM’s OBD.

Thanks GM!


What’s the model year of your sunfire OP? And if there’s an option, what engine does it sport?

So, OP, would you give us more information, answer the questions asked, so we’re not flailing about debating one another here and can focus on helping you solve your problem? Please? :relaxed:

We truly do want to help.

It’s a 2002. I’m not experiencing any problems other than a check engine light. I’m using a scanner I bought on Amazon. All it says is DTC 03 I/M no.

I believe what is being displayed is a status code of the scanner, not a fault code from the car’s computer.

What type and model is your scanner?

Autel MaxiScan MS300.

You haven’t gotten past the introduction screen. That’s telling you there are three DTCs set and I/M data is available. Do you have the manual for it? I see all kinds of complaints people didn’t get the manual with this cheap Chinese product. Here’s a link-

No, thanks. I’ll check it again when the code comes back up, I cleared it. Any idea how long/how many miles that might be?

Your guess is as good as ours, not knowing what the code was before you reset it

My guess is an O2 sensor, or some other emissions nonsense.

Fuel system evap leaks are probably the most common reason reported here for a dtc code to turn on the check engine light. O2 sensor/cat codes probably come next.