error code:9 Atmospheric Pressure sensor.
 

where is it by the ecu? i have a 1988 n/a and iam pulling this code will this affect passing ca emisions?

The ECU is under the floormat on the passanger side.

and the steering wheel is in front of the seat..

It's way above the ECU and to the right of it. It's against the right side of passengers foot well. It looks SIMILAR to the pressure/boost sensor in the engine bay. I'd guess it's at least a foot higher than the ECU.

I'd say it's located about a half foot aft of the engine firewall and inline with the EM harness that passes thru that bulkhead. Find that large grommet that the EM harness passes thru on the firewall, and look aft of the firewall at about the same height as that grommet.

Will it effect emissions? Depends. If your at Sealevel, I'd say NO. Because when it fails or is disconnected, the ECU defaults to sealevel for its signal. If you a few hundred ft above sealevel, then YES it will make the engine run richer because it has defaulted to sealevel.

P.S. I liked the steering wheel in front of the seat remark. Cool.

Just as FYI, I have altered the ATP signal and made one of my engines run leaner/richer as I played with the signal.

If someone has replaced your engine and removed the EM harness to remove the engine, then most likely that was when they failed to reconnect the plug to the ATP.

ok thanks, i did the rebuild and made sure everything was plugged back in iall take a second look

Isn't error 9 the water thermosensor? It is on my s5 t2. On mine, the wires came out of the back of the plug so I had to push em in and make sure that the connectors were touching the sensor.

edit - haha I guess I don't read first posts, but maybe the info can help anyway.

S4 and S5 error codes are different, so no, code 9 is not for the thermosensor on an S4.

i have a few spares if you need one