Fault Code #21 on '95 Dodge Ram 5.2
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Joined: Dec 2006
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From: Central Maine
Fault Code #21 on '95 Dodge Ram 5.2
Today, using the on-off key method, I got a #21 fault code on my 1995 Ram 1500 5.2/5-speed, non-AC, 147k miles. The cause is listed as "O2 sensor does not detect lean or rich conditions, or O2 sensor input voltage too high."
The O2 sensor and wiring look very good, but I have no idea how long it's been since the O2 sensor was replaced, I've put hardly any miles on the truck since I acquired it.It shows almost zerocarbon build-up. I don't have a problem with replacing it, but I am wondering if the sensor itself is bad and/or if this code could also indicate a problem elsewhere that affects the O2 sensor, such as a plugged cat (no rattles).
The truck sometimes goes absolutely flat, no power. If I back off the gas it will sometimes, but not always, come out of it. When it's having its fit, if I push in the clutch it seems to rev freely, but whenI engage the clutch it will go flat again. It'll lurches like crazy at its worst. It always starts good and never stalls under any conditions. Other times it'll snap out of it and run fairly well and strong, but not for long. When it's having its bad spell it likes lower gears and very, very gradual applications of throttle, and sometimes, even that is too much. If I can get the revs up it'll run well for a short distance, but rarelyfor more than 6-8 miles. After letting it warm to normal temperature, for the first 5-10 minutes on the road it will run fairly well, but after that, terrible.
I removed the throttle body and cleaned it thoroughly, blew out the passages with compressed air, and cleanedthe IAC sensor plunger and its chamber/sealing surface in the TB. The IAC plunger is retracted when plugged in but not installed, and with the key on. It hasnew MAP and TPS sensors, air filter, recent plugs, wires, and distributor cap. It has a better quality idle after cleaning the TB and replacing the two sensors, but the bad spells haven't improved at all, it has the same symptoms now as it did before any of thework was done.
I am thinking that I'll replace the O2 sensor, then head for a muffler shop to have them check the cat. Can anyone offer me any other ideas? Thanks for any help.
The O2 sensor and wiring look very good, but I have no idea how long it's been since the O2 sensor was replaced, I've put hardly any miles on the truck since I acquired it.It shows almost zerocarbon build-up. I don't have a problem with replacing it, but I am wondering if the sensor itself is bad and/or if this code could also indicate a problem elsewhere that affects the O2 sensor, such as a plugged cat (no rattles).
The truck sometimes goes absolutely flat, no power. If I back off the gas it will sometimes, but not always, come out of it. When it's having its fit, if I push in the clutch it seems to rev freely, but whenI engage the clutch it will go flat again. It'll lurches like crazy at its worst. It always starts good and never stalls under any conditions. Other times it'll snap out of it and run fairly well and strong, but not for long. When it's having its bad spell it likes lower gears and very, very gradual applications of throttle, and sometimes, even that is too much. If I can get the revs up it'll run well for a short distance, but rarelyfor more than 6-8 miles. After letting it warm to normal temperature, for the first 5-10 minutes on the road it will run fairly well, but after that, terrible.
I removed the throttle body and cleaned it thoroughly, blew out the passages with compressed air, and cleanedthe IAC sensor plunger and its chamber/sealing surface in the TB. The IAC plunger is retracted when plugged in but not installed, and with the key on. It hasnew MAP and TPS sensors, air filter, recent plugs, wires, and distributor cap. It has a better quality idle after cleaning the TB and replacing the two sensors, but the bad spells haven't improved at all, it has the same symptoms now as it did before any of thework was done.
I am thinking that I'll replace the O2 sensor, then head for a muffler shop to have them check the cat. Can anyone offer me any other ideas? Thanks for any help.
