From Ross-Tech Wiki

2.7 Are there any Fault-Codes that can and should be ignored?
Yes. Most 1995 and earlier Bosch ECU's will show you a DTC 00513 - Engine Speed Sensor (G28) if you scan them when the engine is not running. This fault code goes away by itself once you start the engine. If this sensor were truly defective, the engine would not run at all! Please ignore this code.
In addition, many Automatic Transmission Control Modules will show a DTC 00526 or 17087 that indicates a faulty brake light switch. This can also be ignored and will not appear if you press the brakes once before checking for Fault Codes.