PO300

[bronsin]

I have a 2000 ECHO with a PO300 error code.

Can someone advise what to check for? I looked it up and it sounds complicated.

The vacuum lines all appear to be good.

[clarenceie]

I believe the code was P0300, which states multiple misfire. Does your engine feel like it's running weird? Not smooth?

[bronsin]

Runs normal. Mileage was down to 30 from ~34.

[CTScott]

That is one of those codes that can have a bunch of causes:

- Open or short in engine wire harness
- Connector connection
- Vacuum hose connection
- Ignition system
- Injector
- Fuel pressure
- MAF meter
- ECT sensor
- Compression pressure
- Valve clearance
- Valve timing
- PCV valve and hose
- PCV hose connections
- Air induction system
- ECM