2004 Dodge Intrepid



March, 5, 2013 AT 12:30 AM


I am hoping someone can give me some insight on my problem I am currently having. I bought this Ex-Police Car about a week ago and it runs and drives perfect. The only problem I am currently having is that when I had the codes read it was P0172 which tells me the car is running too rich. Basically led me to the BANK 1 O2 Sensors. The Upstream ones on either side of the engine. I just went and spent over $100 on those 2 sensors. Driverside installed and tightened just fine, however, I did not notice until after replacing the passenger side (which are both before the cats) that when I went to install and thread the new one, I figured out that the stupid previous owner obviously didn't care and stripped the threads that the O2 sensor threads into. My question is if anyone can help me out and let me know if I now need to replace the exhaust manifold or what. Any help or input I would appreciate greatly. What would cause the P0172 code on top of O2 sensors? Thanks for any advice

3 Answers



March, 5, 2013 AT 12:50 AM

In all likeliness the o2 is the cause, you can buy a tap that will repair the 02 threads, they sell them everywhere like autozone, advanced. Ect.



March, 5, 2013 AT 12:59 AM

The threads are stripped in the exhaust manifold so not too sure. It has 2 brand new sensors in it I just bought yesterday. I used seafoam and ever since it's been giving same code that its running rich. Idk all the possible causes for this code?



March, 5, 2013 AT 1:19 AM

First lets clarify the designations. You listed two O2 sensors. Bank 1 is the driver's side. Bank 2 is the passenger side. "Upstream" is before the catalytic converters, and "downstream" is right after the converters.

You're getting a code for the driver's side running too rich, and based on the message, you're replacing the messenger. The sensor is working if it's reporting a problem. The way to approach this is to use a scanner that displays live data, and view the left sensor to see what it's reading. It should be bouncing around between 0.2 and 0.8 volts a couple of times per second, and that correlates with switching between "rich" and "lean" a couple of times per second. O2 sensors do not detect fuel, only oxygen, so they do not really detect a rich condition. They fail to detect those lean pulses. Disconnect one injector at a time from the driver's side of the engine to see if the O2 sensor goes lean. If one does not cause that, it may be leaking fuel into the engine. If it is, you won't get a misfire when you unplug that one.

Before you spend any more money on the left side, address the stripped threads on the right side. A leak there can result in the right side reading too lean. Between the pulses of exhaust gas flow, the momentum creates little pulses of vacuum that can draw in outside air. The oxygen in that air gets detected as a lean condition, and the Engine Computer responds by commanding more fuel. No matter how much fuel it adds, there will always be that extra oxygen there.

To fix stripped threads, get a Heli-Coil kit from any auto parts store. It will have the correct size drill bit to drill the hole larger, and the correct size tap to make new threads. You use the special plastic tool to wind the spring-metal insert into the hole. Use a small punch or screwdriver to break the little tab off the end, and there's your new threads. Use a heat-resistant liquid Lock Tite product on the outside of the insert, (before you install it), to keep it in place the next time the sensor is removed.

You might also have luck with JB Weld. That is an epoxy that gets hard as metal, but I don't know how it holds up to that kind of heat. Put some high-temperature anti-seize compound on the threads of the sensor, (if it didn't come with any already), and use a wire brush to clean the hole in the manifold. Coat the hole with the glue and work it into the remaining threads, then run the sensor in. Let it sit overnight. The anti-seize compound will allow the sensor to be removed next time.

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