Doing It Myself

The other day I was driving along and I noticed my Check Engine light was on in my truck. Sad days indeed! The check engine light (or Malfunction Indicator Lamp as we in the know call it) is used to let the driver know that any one of thousands of things is going wrong with your car and you should take it to the shop and give them a blank check. Being the do it myself kinda guy that I am I didn’t WANT to take it to the shop and give them a blank check so I started reading. I soon found out that since 1996 every car sold in the United States is required to support a diagnostics specification called OBD II. Additionally, the OBD II port is standard and must be within 3 feet of the steering wheel inside the driver area.

A little more reading led me to learn that there are 3 protocols supported in OBD (with more being added now and then) and that my Ford Ranger supported SAE J1850. Alas! That sounds familiar indeed. That’s the same protocol that Ford uses to talk to their CD changers and I have been working on a project to speak it! Unfortunatly that project is not done and I was in a hurry to get my truck happy again.

I did some research and found you can have a OBD II code scanner for anywhere from $49 through several thousand. There is one interface available that I found that will do all the available protocols and talk to your PC via a serial port for $88 which had I the time would definitly have been my choice but instead I ran down to O’Reilly Auto Parts and picked up the one they sold for $150.

My impulsiveness is a crutch 🙁

Anyway, $150 later and my car is trying to tell me P0401 Exhaust Gas Recirculation Flow Insufficient Detected. Sounds like something to be ignored to me. I erased that sonofabitch and the Check Engine light went off. If it comes back on I’ll worry about it but for now I have reduced my stress.

There is a long story about why I own a Ford truck when I HATE Ford trucks, but I’m not going to get into it. Suffice to say I think domestic cars are all shit and I would not own one if I didn’t have to. My opinion is that they break down too often, and are just unreliable. This brings me to why I am willing to spend $150 on something that I could have had a mechanic check out. I fully expect that my Ford truck will show me it’s bad side again in the future and instead of paying (at least!) $50 each time it does for the mechanic to tell me what is wrong I’d rather just have the power. It also appeals to the unstoppable geek in me to be able to see what my car is doing all the time, and what is making it sad.

So anyway, yea, if your car’s check engine light comes on and you don’t want to take it to a mechanic just to find out that it’s some part you can replace for $10, grab an “OBD II Code Scanner” from your local auto parts store and give it a shot. This one looks really nice and shows a lot more than what mine is able to, but requires a laptop. Of course, if you are reading this you are probably a friend of mine and you are welcome to use mine 🙂

5 thoughts on “Doing It Myself”

  1. I have a ’99 Ford Ranger and several weeks ago the Check Engine warning light came on. A friend of mine had a tester and it indicated “exhaust gas recirculation flow insufficient”. So what do I do about it? Is there an EGR valve I need to replace — or does a vacuum modulater need to be replaced — or is a sensor faulty?? Thanks for your reply.

  2. Ken – When I had the same error the reasearch I did indicated that the EGR differential pressure sensor needed to be replaced. Unfortunatly I didn’t really keep notes, but if you search for the error code (P1023, if I remember correctly) you should be able to find the same information. The part ran about $85 new, I think.

    Shawn – The protocol is called J-1850 and is available from SAE for $12.50. It’s also sometimes referred to as ACP. It’s basically RS-485 serial with differential signaling at 9600 baud.

  3. I own a 2001 Ford F150. My scanner reports codes P0401
    and P0402. The first indicates excessive exhaust gas, the
    second indicates insufficent exhaust gas. I removed and
    cleaned the egr valve, replaced the gasket, reset the obd II.
    After driving a few miles, the nasty “check engine” light came back on. Anyone got an idea what I should do next
    (besides selling my pickup)? TIA

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