Diagnosing Check Engine Light without tool?

[mark2000]

Is it possible to diagnose the codes from the Check Engine light without the OBD computer tool?

On my old Saturn, you could jumper a circuit and the dashboard lights would flash in a sequence that indicated which error code it was.

My light came on today as I was driving, it started flashing for about 10 seconds and has stayed on since. My automatic 2003 P5 is shifting roughly from 1 to 2, and runs rough at idle, almost stalling. Judging by what I have read, its looking like the EGR value, a cracked hose, or some coil thingie.

It only has about 126,000 KMs on it.

 

[Cosmic Wonder]

Someone else can chime in about the light being able to tell you the code but I'll bet it's probably P0300-0304 (random misfire or specific cylinder misfire) and is probably coil packs, spark plugs or wires...or all 3.

 

[tweety2300]

It is not possible to do on an obd2. However blinking cel is a misfire.

You can use the jumper on an obd1 car.

And obd0 the ecu has an led that blinks to say the code

 

[mark2000]

These devices cost about $200 at Canadian Tire, I am wondering if its worth doing a buy-and-return to check the CEL.

If it is a misfire, couldn't it be caused by many things? What makes it "probably" the coil packs and spark plugs/wires, versus a stuck EGR valve?

At any rate, I am going to reset the car's computer with the battery and hope that the light doesn't come back on for awhile. The problem doesn't seem to be consistent, so maybe it will "fix itself".

 

[Cosmic Wonder]

I said "probably" because if you're at 126,000km then you're basically overdue for at least one of the items I listed. All three items are easy to replace for the DIY'er with basic tools (socket set, etc). Don't get me wrong, I'm not saying it isn't the EGR at all, but everything I've read on this forum has listed those three items fail around or before that time. Also, my car had a very similar symptom as yours recently but I have an UltraGauge hooked up which told me exactly it was a random misfire. Replaced the coil packs that night in 15 minutes and it fixed it. I will be replacing the plugs and wires shortly as a precaution. $15 for plugs and a $50 for a set of wires I figure is cheap insurance.

 

[mark2000]

What do you think of this strategy:

- Check and clean EGR if necessary, reset engine light and test drive to see if fixed.
- If not fixed, then move to plugs, wires and coil packs and test again.

I will have to do the plugs and wires soon I guess, but I'd like to just get the immediate problem fixed, so this is what I'm thinking.

You mentioned plugs and wires are about $65, what about the coil packs? How many are there and what's the cost for the part there?

Thx.

 

[tweety2300]

If you ignore it and wait to fix it your going to destroy your Pre cat if you don't want to pay $200 try $1,000

 

[pkane]

You can get an OBD reader for about $50 online.

 

[Fresco]

You can get an OBD reader for about $50 online.

even less if you have an android phone $5 for the torque app and $15 for a bluetooth obd2 reader from ebay...its what i use and works better then most $200+ scanners

 

[Cosmic Wonder]

Mark,
I'm assuming you're in Canada as you mentioned your mileage in km, not miles. I, too, am in Canada, Vancouver actually. I paid $62 each for the coil from Lordco in B.C. (2 required, located right on top of the engine and held on with a single 10mm bolt, literally took me 15 minutes from the minute I opened the door to the car to open the hood until I started the car with the CEL cleared to test it). The coils can be found cheaper online (rockauto.com) but I wasn't willing to wait a few days as I need my car daily. And like tweety said, if you run your car with a misfire you will destroy the precat which isn't cheap, as he mentioned. If it were me, I'd replace the coils first and maybe the plugs with NGK V-Power part #BKR5E-11 while you have the coils off and reset the car (disconnect the battery for 5 minutes) and try that. It's not a matter of if the coils will quit, it's a matter of when.

 

[mark2000]

Thank you all for the continued response.

Sounds like the plugs, coils and wires should be the priority for now then.

Question though: How would bad plugs, wires and coils affect a pre-cat? As I understand it, the pre-cat handles exhaust, fumes and gases. Fumes don't run through wires and plugs, so where's the relationship there?

 

[Cosmic Wonder]

The failure of the precat happens due to the misfire....unburned gases exhausting from the engine and clogging up the precat. The failure is determined by the two O2 (oxygen) sensors (before and after the precat). There is a "fix" on here for precat failure to fool the ECU into thinking it's working fine. If you search "non-fouler" you should find it. It explains it more in depth.

If you're on a tighter budget like I am (wedding planning...nuff said lol) then you can do them in stages, try coils first and if that fixes it plan for plugs and wires shortly. Then you can clean the EGR at the same time.

 

[mark2000]

Luckily I just passed emissions before this all happened ... like two weeks ago, so I'm in the clear there. Phew.

 

[mark2000]

Hey all!

Well, I'm going to take y'all advice and get the OBD tool for diagnosis. Is there code(s) I will more likely see if it is the ignition coil packs than anything else (like the EGR)?

The packs are special order for about $60 each at Canadian Tire, which is walking distance to me. I'm afraid to drive the car to a cheaper parts dealer because I don't want to ruin anything else. After seeing the check engine light flash, I drove about 6 KM to get the rest of the way home. Is that enough to destroy the CAT?

And also, when I remove the old coils, are there usually indicators or evidence that they were broken? i.e. will I see rust in them, smell fuel, etc.

It would be nice to get away with just having to replace one rather than both, if only one was broke.

 

[mark2000]

The code is P0304. If I'm standing, facing the engine outside the front of the car (i.e. with the driver's side to my right), which spark plug is number 4, the one on the right or the left?

And which ignition pack corresponds to spark plug 4, the one on the left (passenger's side) or right?

I plan to replace everything eventually, but want to start with the offending parts first, to make sure I'm not out of my league here. I did this stuff before on my Saturn, but this is a first for the Mazda. If this doesn't fix the problem, then I'll probably be relegated to paying mechanics' fees.

 

[mark2000]

Sorry to bug y'all again but I really need some advice urgently. I've been working on this since my last post, and decided to swap the coil packs in an effort to pinpoint the problem. I figured if it was a coilpack, the misfire would have happened on another cylinder than #4.

After the swap, the car ran even rougher than it did before. Engine is lurching and stuttering (although no stall!). It's struggling to get power when I accelerate. I cleared the codes, and got a P0300 after swapping the coils. I then cleared them again and now P0304 is showing up again.

Any ideas on what should I do next? What it could be?

 

[tweety2300]

Plug wires or plugs I can't remember which cylinder the coil packs sit on they really should be replaced anyway if you have the money. P0300 is random so you may have gotten bad coil packs. Clean your egr valve I rememb er a couple people getting p0300 for it being bad. Also you need to reset your ecu by unhooking the battery. It learned to idle with a misfire so now it's idle ing bad because it has to re learn.

 

[rjmhotrod]

Double check your air intake hose, between the filter and the motor. That will get brittle and crack after 7-8 years or so (it did for me). If you find a crack, you can simply wrap duct tape around the hose until you order a replacement part. Also, the last time I had a misfire I replaced the packs, coils, wires and plugs. It was closing in on 100k miles anyway so it needed to be done. And most parts stores will analyze your codes for free - no need to buy a scanner unless you just really want one.

 

[CheeseHelmet]

Sorry to bug y'all again but I really need some advice urgently. I've been working on this since my last post, and decided to swap the coil packs in an effort to pinpoint the problem. I figured if it was a coilpack, the misfire would have happened on another cylinder than #4.

After the swap, the car ran even rougher than it did before. Engine is lurching and stuttering (although no stall!). It's struggling to get power when I accelerate. I cleared the codes, and got a P0300 after swapping the coils. I then cleared them again and now P0304 is showing up again.

Any ideas on what should I do next? What it could be?

Get new ignition coils, wires, and spark plugs. The longer you wait, the more you damage your primary catalytic converter.

 

[tweety2300]

It's actually the precat...