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Old April 9th, 2019, 17:52
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Tacowhip Tacowhip is offline
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Intermittent 21 code.

Hey guys. Iím getting an intermittent 21 code, Oxygen sensor. Itís been throwing this code ever since Iíve bought the Jeep 3 years ago. I replaced it with an NTK. Still throwing the code. Any body have any information on this issue, or a wiring diagram, possible fuses? Thereís also a 12 code thatís always there. Rarely do I disconnect the battery. Itís a 95 sport 4.0. Thanks.
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Old April 9th, 2019, 18:21
lawsoncl lawsoncl is online now
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Re: Intermittent 21 code.

Have a good look at the wiring and make sure it's not hitting the exhaust and shorting out. If it's not secured well, it can melt against the exhaust manifold.
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Old April 9th, 2019, 18:56
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Tacowhip Tacowhip is offline
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Intermittent 21 code.

The wiring is zip tied away from the exhaust and not rubbing anything. All good there

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Old April 11th, 2019, 18:39
Dragonslayer Dragonslayer is offline
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Re: Intermittent 21 code.

Check the O2 harness where it exits the end of the square plastic wire harness tube that is near to exhaust tube #1. Often a previous mechanic will route the O2 sensor wire too
near to the exhaust tube and fry the wires, and then perform a dodgy repair. Open up
the black plastic corrugated split cover (wire harness) starting at this point and follow it
down to the sensor. Inspect for anything that looks stupid, or out of the ordinarily.

This happened on my car. After months of fiddling around, and 3 new O2 sensor$, I checked
the wires there and found a wire harness repair done by a previous owner using Romex
home wires and non-insulated crimped connectors! All was good after correcting this with
proper wires, and twisted & soldered splices, and double layers of heat shrink tubing.
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