OzzyNF

I have gotten the 430 engine code and I was wondering how many 02 sensor the cherokee has? best brand to use?

dnuccio

i think theres 4

5-90

Probably a total of four - two upstream, and two downstream.

However, the code itself should tell you WHICH sensor it applies to!

It should also be noted that the two "upstream" sensors (closest to the engine) monitor fuel trim and can affect fuel economy, while the "downstream" sensors (after the catalytic converters) are merely there to monitor catalyst efficiency.

Spec life on the UHEGO (Upstream Heated Exhaust Gas Oxygen) sensor is typically 60,000-75,000 miles. If one wants replacing, it's best to replace both.

Spec life on the DHEGO (Downstream Heated Exhaust Gas Oxygen) sensor is similar, but there's rather more "give" there - I wouldn't push it past 100kmiles on OBD-II, tho.

The use of a quality OEMR direct-fit HEGO is recommended, I prefer Bosch or NGK. ACDelco is also acceptable (I think they're reboxed Bosch parts anyhow.)

- Get a HEGO sensor socket, if you do not already have one.
- The new sensor should come with never-seez on the threads or in a small packet - use it! If it does not, buy it and use it!
- Remove the old sensors while the exhaust is as hot as you can stand being near.
- Use a torque wrench for installation - torque to 19-21 pound-feet (typical installation value for a HEGO with never-seez on the threads,) and no more! You want to be able to replace it next time, don't you? I've had to machine out busted HEGO sensors because someone got stupid with install torque... This job isn't cheap - especially since people often insist on my doing it in situ - in the driveway, with parts in place.
- After the sensor is properly installed, be sure to reroute the wiring along the OEM path, so it stays off of the exhaust manifold. If you can, the addition of a heat-resistant wire covering won't go amiss - you can often find this in speed shops, meant for installation over plug wires (but it can also be installed over other wiring and hoses.)

Despite these caveats, the job is actually rather simple on most vehicles. It typically takes me longer to get to the damned sensor than to replace the thing!

EDIT - if you need leverage, I find it useful to use a flare nut wrench that fits (typically 7/8", may be 22mm or so in uncommon cases) to get a good pull on the thing. If you don't have a flare nut wrench, you're better off cutting the OEM wiring at the sensor end and fitting a six-point box wrench over the thing, vice screwing it up with an open-end or 12-point box wrench!

jnicewan

Codes P0420,P0430 are specific codes for catalyst efficiency. The PCM measures readings from the catalyst monitors (downstream oxygen sensors) in order to check the catalysts for emissions compliance. There are numerous other codes that are usually associated with other running concerns or sensor circuit faults or sensor failures.

Very rarely are these codes generated for something other than actual catalyst failure. This code doesn't mean the catalytic convertor is stopped up, it simply means its not cleaning up the exhaust emissions to a set standard. P0430 is bank 2 catalyst efficiency, thats the drivers side cat. The sensor that trips this code is the rear sensor (downstream) on the drivers side (H02S-22). If you feel like you should try replacing these sensors, then you can at least save a few bucks and only replace the driver side rear, or both drivers side sensors.

OzzyNF

Thanks guys..great help