Tuesday, March 25, 2008

How I fixed the P0420 code on my 1998 Honda Accord EX

Is your check engine light on with a code P0420 and you don’t know what to do? Then you probably find yourself in the same situation I did a few months ago. While driving my 1998 Honda Accord, I noticed that the check engine light came on so I took it to the auto parts store to have the code read for free. They said I had a P0420 code which meant “catalytic converter efficiency blow threshold.” So, I looked on the internet and found lots of information scattered everywhere but no real answer on what to do.

After doing a lot of research, I developed a list of things to check. I wanted to make sure I ruled out all the inexpensive and simple options before replacing a major component. This is the list I came up with and I hope you find it helpful. I must let you know that I am not a mechanic and I have no training in this area however I am a fairly handy person and I did a good deal of research on this topic. Also, I make specific reference to my 1998 Honda Accord EX but I believe this list generally applies to most cars.

Before you do any work check to see if your car is still under warranty. According to federal law all catalytic converts have an eight year or 80,000 mile warranty. Additionally, Honda agreed to extend the warranty on emissions components to 14 years or 150,000 miles on most 95-97 vehicles. The lest most inexpensive option is to have it serviced under warranty!

For more information on how the emissions system works see these links:

Step 1: Buy the Manual.
If you have spent anytime on forums asking questions the first response you get is always “get the manual.” This is good advice. Throughout this blog I make reference to the Hayne’s Manual for my 1998 Accord. So if you want to follow along and do the work you will need it.

Step 2: Find Other Symptoms.
To accurately diagnose and fix the problem you need as much information as possible. Have you noticed anything different about the way your car runs? Here are some common symptoms

Loss of power: this may indicate your catalytic converter is clogged and must be replaced. However, you should confirm this with a vacuum pressure check before spending the big bucks on a new converter (see step 4).

Blue tailpipe emissions: this may mean that your engine is burning coolant which can ruin the catalytic converter. Check your coolant level every other day for a week or two and see if the level gets lower and lower. Unfortunately, if your engine burns coolant you must fix this problem first and then replace the catalytic converter. If you don’t fix the coolant leak the new converter will suffer the same fate as the last one.

Keep in mind, however, that these symptoms don’t necessarily mean your converter is blocked or your engine is leaking coolant. You must confirm with other tests like the vacuum pressure check and coolant level check. Don’t assume the worst most expensive option rather exclude less expensive options first.

Fortunately my car didn’t have either of these problems!

Step 3: Reset the Check Engine Light.
Resetting the Check Engine Light is the easiest solution. Sometimes your car’s computer (ECM) simply freaks out and gives you this code when there is no real problem. So before going any further reset the ECM and see if the Check Engine Light comes back on. You should also reset the code after you make any repairs. If it doesn’t come back on, your finished!

To reset the light, open the passenger side door and look for a panel on the far right hand side of the dash. The panel is covered by the door when the door is closed. After popping out the panel, remove the fuse in the number 13 slot for at least 10 seconds. The numbers on the fuse themselves represent the load the fuse can handle without blowing not the slot number. The slot number is printed in between the rows of fuses (see pictures below).

Keep in mind, however, that you can not reset the code and immediately take the emissions test. You wont pass. The computer must show that your catalytic converter came on and functioned properly. For the converter to reach light off temperature normally requires some combination of city and highway driving. So take your car for a drive on the interstate for 30min first.

Step 4: Component Check.
Now you need to check the various components of the system to see if any aren’t working properly.

First, inspect the exhaust system (CAUTION: let the car cool for a least 3 hours before doing this inspection and make sure it is securely on safety stands or ramps). Sometimes a leak or hole between the two O2 sensors can allow outside air to mix with the exhaust gases causing a false reading and setting this code. Look for discolored areas where parts are joined together, excessive rust, loose connections, and bent/crushed pipes. Some rust is normal. Then run your hand along the pipes feeling for any holes. Repair as necessary. Also, knock on the converter with your knuckles. If you hear rattling inside the converter then it is damaged and must be replaced.

Second, check the O2 sensors by following the Hayne’s Manuel. You normally check for three things 1)the sensor switches out of open loop—it rapidly switches voltage between 0.2v and 0.8v 2) the sensor has the proper resistance 3)the sensor is getting enough power i.e. 12.5v where it is connected. The first two problems mean a bad sensor the third indicates an electrical problem.

Sensors slowly deteriorate and become sluggish so that they don’t switch voltages as quickly as they should. This sluggishness can cause the P0420 code instead of a bad sensor code because the sensors works well enough to pass the sensor test but don’t match up with each other. My Honda uses a 4 wire preheated 02 sensor which has an expected life of about 100,000 miles. My car had 133,000 miles so I put in two new sensors which fixed the problem. So if your car has 85,000+ miles on it, you should switch out the sensors before going any further (I used Boshe universal O2 sensors which cost $70 each; OEM sensors run $100+).

Front sensor:

Rear sensor in the catalytic converter:

Connection for the rear sensor:

Third, check the electrical system (if both 02 sensors have the correct voltage at the connection you can skip this step). If one O2 sensor has the correct voltage but the other doesn’t, check the wire and connection between the sensor and ECU. Otherwise, check to see if you battery is fully charged and that your alternator is working properly. Most parts stores have a machine that can test the alternator without removing it from the car.

Step 5: Check the Catalytic Converter.
If you have gotten this far your converter has probably gone bad. You have ruled out most other causes and you may opt to go ahead and replace the converter without further testing. However, it can still be a good idea to confirm your findings. There are two possible problems and two ways to check.

A blocked converter: following the instructions in the Hanye’s manual hook up the vacuum gauge and note the pressure (I bought a vacuum gauge for $25). Then rev the engine four times. If the pressure after revving the engine is more than 1 UNIT below the pressure at idol, some component of your exhaust system is clogged. You can then disconnect the converter on the muffler side and letting it hang down perform the test again. If it passes, the converter is not clogged. Otherwise, totally disconnect the converter and do the test. If the car passes the test with the converter disconnected but not with it connected you know that the converter is clogged and must be replaced.

A poisoned converter: unfortunately checking to see if the converter actually converts gases requires thousands of dollars of equipment. Many shops may charge you as much as $100 to do the test. If you have ruled out every other option, you should save your $100 and uses it towards the price of a new converter.

You can spend wildly different amounts on a new converter. I direct replacement from the dealer for my 1998 accord was $675 just for parts. However, I found an aftermarket direct fit replacement for $220. You can buy universal converters for even less but if you don’t have welding equipment, you wont get very far.

LEGAL NOTICE: All this information is for educational purposes only. I assume no responsibility for any repairs or damages. You assume full risk and responsibility should you decide to act on any of this material.

Thursday, December 20, 2007

That Crazy Gold Bug!

Mainstream pundits love to criticize Ron Paul for his outspoken support of sound-money and the gold standard. Normally, they simply call Ron Paul names like crazy, fringe, or anti-intellectual (my favorite). Now we are beginning to see the next wave which actually contains some arguments. Salon.com's Andrew Leonard launches the latest attack by appealing to the consensus.
Mainstream economists will be happy to argue about whether, at any particular point in time, the Fed is too eager to ease interest rates and prop up speculative bubbles. But few would suggest that the solution is getting rid of the Fed altogether, and even fewer that returning to the gold standard is a workable option.
Leonard correctly sees that most 'mainstream' economists disagree with Paul. Yet, many world renowned economists do agree with Paul--Freadrich Hayek, Milton Freedman, and Lidwig von Mises. Perhaps the most interesting endorsement of Paul's position comes from Mr. Fed himself Allen Greenspan, whom all these pundits worship as an economic god. Before becoming the Fed chairman, Greenspan wrote a short article "Gold and Economic Freedom." He concludes
In the absence of the gold standard, there is no way to protect savings from confiscation through inflation. There is no safe store of value. ... Deficit spending is simply a scheme for the confiscation of wealth. Gold stands in the way of this insidious process. It stands as a protector of property rights. If one grasps this, one has no difficulty in understanding the statists' antagonism toward the gold standard.
Although Greenspan pined this while still young, he has confirmed he still holds this position. During a Congressional oversight meeting the following exchange occurred:
‘Now my next question is, is it your
intention that the report of this hearing should be that Greenspan recommends a return to
the gold standard?’ Greenspan responded, ‘I’ve been recommending that for years, there’s
nothing new about that. . . . It would probably mean there is only one vote in the Federal
Open Market Committee for that, but it is mine.'
Ron Paul reportedly asked Greenspan if he still believed the pamphlet. Greenspan responded that he recently re-read it and "wouldn't change a word of it."

So, we can either consider Greenspan a crazy, fringe, anti-intellectual gold bug or give Ron Paul a fair hearing.

Some ancient wisdom to ponder during this election cycle.

Those who rule shall be like sea monsters,
swallowing up human beings like fish.
Free sons and daughters they shall enslave;
houses, fields, flocks, goods they shall seize.
With the flesh of many persons they shall wickedly
gorge crows and cranes.
They shall make progress in evil; they shall
be exalted in avarice
(Testament of Judah 21:7-8; 2nd Century BC).


I found this very interesting text where Solomon interviews Belzelboul, the Prince of the demons.

I said to him, "what are your activities?" He replied, "I bring destruction by means of tyrants; I cause the demons to be worshiped alongside men; and I arouse desire in holy men and select priests. I bring about jealousies and murders in a country, and I instigate wars." (Testament of Solomon 6:4; 1st-3rd century AD)

Saturday, December 15, 2007

Review: Williams Hebrew Syntax

Today, I reviewed Williams Hebrew Syntax at amazon. I have included the review below.

Beckman thoroughly revised and expanded Williams’ original work without losing it’s genius. He includes a concise and informative explanation for each grammatical category and gives a literal interlinear and idiomatic translation for every example. Beckman has helped all future Hebrew students with his extensive footnotes. For every category, he gives a footnote with the section number of the same category in the five major reference grammars—A Biblical Hebrew Reference Grammar, Guide to Biblical Hebrew Syntax, Gesenius, Introduction to Biblical Hebrew Syntax, and Jo√ľon. Thus, he made his grammar into an index of all grammars.

Despite these advances, I have one minor criticism. The authors do no include a separate section on hinneh, “behold.” This particle plays a key role in many constructions as evidenced in the grammar. However, the student must flip though the whole book to find these uses when they should be together. Perhaps the authors left this out to save space but they could at least include hinneh in the Hebrew word or subject indexes. I hope a future edition could correct this very minor oversight

I use this grammar every time I read Hebrew. When I arrive at a construction I need help with, I reach for William’s Hebrew Syntax first. Usually, I am satisfied with his description but if I need more I use his footnotes to quickly find the appropriate section in an advanced grammar. Beckman has made a grammar that is ideal for quick reading while also acting as gateway to more advanced study. I recommend all students buy Williams Hebrew Syntax and either Bruce K. Waltke and M. O'Connor An Introduction to Biblical Hebrew Syntax or Paul Jouon and T. Muraoka A Grammar of Biblical Hebrew. With this combination, you can quickly look up constructions without flipping though thousands of pages and still have access to advanced information when you need it.

Sunday, November 25, 2007

Second Temple Judaism Listmainia

The Second Temple Jewish period provides the key to understanding the New Testament. Before we can apply the teaching of scripture today, we have to know how the original audience understood it. In order to read the New Testament like the original audience, we must read the text with their worldview, presuppositions, and hopes. We can only acquire this ability by immersing ourselves in their culture by reading the primary text from the period.

With this in mind, I have created an amazon.com listmania to guide you through these primary resources. I recommend that you begin by reading "Backgrounds of Early Christianity" then "The New Testament and the People of God." Once you have finished these introductions, read the Apocrypha paying special attention to the books of Maccabees and the first three books of "Jewish War" by Josephus. These sources give you a general historical timeline in which you can place the other writings. Now you can read whatever you like in any order. Please feel free to comment on any suggestions or works I should include in the list.

Saturday, November 24, 2007

Hello all. Samantha put together a baby registry for Elijah's first Christmas you can find it here.

Wednesday, November 21, 2007

When I started graduate school, I decided to brush up on a few basic skills. I thought that if I could read a book quickly, understand what it says, remember the message, and write clearly about it, I would do very well. With this in mind, I assembled a list of books to teach me these skills. I must say that this was a great idea and I have been able to make very good grades at a top notch school while still having a life. Now, I want to share this knowledge with you. I have created an amazon.com listmaina with the books I found helpful. If you read these books and do the exercises, you will do better in school. I only wish I had done this when I started collage! Take some time to look over my listmainia and let me know what you think. What books would you add?

Do well in School and Life