Self-explanatory. I installed a 4.7 ohm resistor to make the 401 code go away and now my car throws a 402 code as a direct result. I changed nothing mechanically so it wouldn't actually be excessive flow. Anything I can do to resolve this?
Resistor trick (P0401) causes p0402
- Thread starter ATXnative
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Malleus
Far west of Siegen
The short answer is to remove the resistor. Why did you choose to use this method to resolve the P0401?
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- #3
I chose this method because my troubleshooting told me it's the temp sensor that is faulty, and there is sufficient flow (the ports are fine, the VSV is fine, the valves are fine, etc). It was the cheaper and easier way, rather than paying a silly amount of money for a new temp sensor. Many other people have put in the resistor without the 402 popping up, and I'm wondering why mine is triggering that code when it isn't with others.
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We have had 100% success with 4.7K ohm resistors.
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- #5
Right, which is what I have been seeing and why I am confused. I have only had a 401 before, and used this resistor: https://www.amazon.com/gp/product/B01D0GEWC2/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
It solved my 401, but now the 402 pops up. When I read the FSM, it seems like I should not have the 402 pop up so long as the resistance at warm-up is 2.5 or more. So I am stumped....
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2.5K ohm or more. K = thousand, so 4.7K ohm = 4700 ohm.
Like this: https://www.amazon.com/4-7K-Watt-Ca...546&sr=1-6&keywords=4.7k+Ohm+Resistors,+1/4+W
Malleus
Far west of Siegen
OK, the reason I asked is that one of the potential causes for the P0402 is a short in the EGR circuit.
If the resistor installation is responsible for this (not the resistor per se, but the sequence of operations related to installation), you may want to go back and check your work.
I'm not criticizing your choice, just trying to offer troubleshooting ideas.
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- #8
Didn't take it as a criticism, so no worries, I def acknowledge trying to take the cheap way out. How would I go about checking a short in the EGR circuit from the operation? Do you mean the way I installed it? I cleared the 401 code, installed the resistor, and then did the driving cycle (warm-up, 50 mph, warm down, 2x).
Malleus
Far west of Siegen
I was thinking more along the lines that a wire is crossed or grounded somewhere. At this point, not having been there, I'd lean towards removing the resistor and checking the circuit. As you can see from the EWD above, the EGR sensor has this resistor in it. What you're trying to do is bypass the sensor circuit and install the resistor, logically, in the position in the circuit it would be in if the sensor, and the engine, were operating correctly.
I'd also recommend checking the resistor, outside the circuit.
HTH
I'd also recommend checking the resistor, outside the circuit.
HTH
You essentially have a short in the circuit, because you used the wrong resistor.
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- #11
This in all fairness may be the issue. I just stuck the resistor in and halfway put the plug covers back together with some duct tape, so the resistor may be touching the temp side plug and shorting/grounding. I will get some some wire connectors and make sure they are insulated. So you know if there is an AWG or AMP range I should be within? I think I have 14 gauge, 15Amp connectors
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- #12
DOH! I missed that there wasn't a "K" on the resistor...yea I feel like a dummy
Malleus
Far west of Siegen
FWIW,
inkpot
SILVER Star
YUP! Just move that little ol decimal point over to the right about 3 positions and I would bet it works a lot better.
Reviewing Malleus' thread above makes me ask the question what does the intake temp air stream temp run for each of our applications? Looks like the 6.4 to 10k would work for everyone on a delete unless you were in Death Valley. Anyone know if Death Valley would yield 302 degree F intake temps?
Plenty hot in AZ where Tools lives...
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Intake air temp has nothing to do with it, it measures the temp of the EGR port flow.
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- #18
Correct, it's the temperature of the 1FZ smelling its own farts
inkpot
SILVER Star
EXACTLY!
Wouldn't that be higher with higher ambient air temps? The exhaust gas temps are lower with 28 degree F intake air than with 115 degree F ambient air.
Has anyone ever thought about sticking the EGR temp sensor in the end of the EGR up pipe after removal of the EGR? It would read a temp but I guess with the EGR removed it would trip the CEL for low or no flow.
