Original post by: Eric Viitala ,
When you change engine oil and filter it is normal for an engine to take a few seconds to read pressure. Assuming all was fine before you changed oil, @jimfixer has your solution. Check your oil level. If oil level and filter are fine, you need to use an obd II diagnostic machine that can read "live data" from the vehicle. It will show your oil pressure. If the sender is bad, the location depends on what engine is in your H2. Usually on the back edge of motor, just behind the intake manifold on GM engines.