Wills98MaxSE

OK after running dianostics 3 times, I kept ending up w/ this error code:

0409

After looking up the code via the procedures in the post "ECU fault code diagnosis," it says "Undefined", can some-1 tell me what a 0409 error code means & if it should be fixed asap?

I'm thinking about getting a 2nd opinion, prob. see one of my dad's mechanics this Fri. & have him do the diagnostic test as well.

As for the SES light, earlier this week (Monday) it came on and just today it went off, and earlier I spoke to my service advisor at the dealer, he asked if my fuel cap is on tight & if the light is flashing or solid, I told him the fuel cap is on tight & the light is a solid on, and he says something emission-wise is causing an intermittent problem to cause my SES light to come on and later on it thinks there's nothing wrong & off goes the SES light. This last happened to me about 2 months ago where my SES light was on for about a week then went off on it's own, this time it was only on for 2 days then again it shut itself off so not to confuse any-1, but can some-1 help me out here?

JustTry

Upstream oxygen sensor circuit slow response fault (right bank)

Wills98MaxSE

JustTry -

thanx for helping me out, the SES light came back on me last week and re-diagnosed, same 0409 error code, does this mean the sensor itself is bad or is ti soemthing within that region you specified, and is there any specific part # for this sensor I can get from the dealer?

SLC I30t

iTrader: (1)

DTC 0409

Diagnostic Trouble Code 0409 indicates a problem with the front Oxygen Sensor on the right cylinder bank.

The right bank is also called the rear bank. It is cylinders 1,3,5. The Engine Control Module determined that the response of the voltage signal from the sensor takes more time than it should. In simple terms, the Oxygen
Sensor is still working but it is not doing its job well. Possible causes include ...
- Harness or connectors (the sensor circuit is open or shorted).
- Bad Oxygen Sensor sensing element
- Bad Oxygen Sensor heater
- Fuel pressure out of spec
- Fuel injector malfunction
- Intake air leaks
- Exhaust gas leaks
- Positive Crankcase Ventilation valve
- Mass Air Flow Sensor



The Oxygen Sensor sensing element may be tested with an electronic tester made for this purpose, or with an
automotive oscilloscope. The Oxygen Sensor heater my be tested with an ohmmeter. This test is done with the
engine off. Follow the wires away from the Oxygen Sensor until you find the nearest electrical connector. Disconnect theconnector. Viewed with the connector latch at the 12 o'clock position, there are three terminals.

They are numbered 1-3, right to left. Be sure to measure the terminals in the connector half which is attached to the
Oxygen Sensor, not the one which leads to the Engine Control Unit.

Measure the resistance between terminals 1 and 3.
The factory spec is 2.3-4.3 ohms at 77 degrees Fahrenheit.

Measure the resistance between terminals 1 and 2.
The reading should be infinity (no connection).

Measure the resistance between terminals 2 and 3.
The reading should be infinity (no connection).