96 dakota 318. got a check engine lite, replaced o2 sensor. lite came on about 100 miles later, code says, engine running rich(code 52). Now what?? reset code, anywhere from 40 to 200 miles later, check engine lite comes on, (code 52), running too rich. STUCK??? HELP!!!

I don't know witch ones but some models came with two O2 sensers.Also check the plug and cable for damage.How does it run and idle

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88 2.2 5SP
95 5.2 Mag
A518
8 1/4
Electronic ignition
Custom EFI (megasquirt 2.2)

Your truck is a '96 which means it is OBDII certified. Which means that you have a few more sensors than us older trucks do. It also means that you don't get sniffed for emissions. It is possible to have another O2 sensor other than the one you replaced.

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Some trucks have both an upstream and another downstream of the cat

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88 2.2 5SP
95 5.2 Mag
A518
8 1/4
Electronic ignition
Custom EFI (megasquirt 2.2)

The one downstream of the cat doesn't have much to do with the A/F ratio - it's job is to verify that there's a change in a/f due to the cat. In other words it just makes sure the cat is doing it's job.

If it's running rich I'd look into your usual tune-up items but also if you've got a buddy see if he'll swap MAF's with you. Perhaps you've got an injector stuck open?

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99 WJ Laredo v8 4x4

91 Mustang GT Roadster

90 Miata

05 Legacy GT Limited wagon

Thanks guys. finally gave up, & took it to the dealer. The upstream o2 sensor, was wired in wrong. Apparently, my friend that put it in, just wired the connector without checking, & connected the sensor wire to the heater, & the heater wire to the sensor. They switched the two wires, & NO MORE LIGHT!! Thanks again.