P0205, P0300, P0303, and P0305 codes: What should I do?

TexasTJ2K

TexasTJ2K

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I have a 2000 TJ, 4.0L, 5spd with the check engine light on. Sometimes, it will start blinking for a short time then return to solid again. Here are the codes I'm throwing:

P0205
P0300
P0303
P0305

So far, I've done the following: all new spark plugs, coil pack, cam shaft position sensor, and crank shaft position sensor. They've helped with the misfires but not gotten rid of them.
Also, there's an issue that I'm sure is being caused by these codes, but when the engine reaches operating temperature around 210, my engine will cut out after 3,000rpm. If I upshift it will start again, but when I hit 3k rpms the engine won't respond to anything. It doesn't shut off, but pumping the gas causes nothing and I am forced to shift.

Any help is greatly appreciated. Next up, I'm going to move around some of the injectors to see if the issue follows the injector or if it's something else. I was also told by a buddy who helps me with repairs that it could be the head gasket.

Thank you.
 
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What causes the P0205 code?
  • Shorted or open wiring harness
  • Fuel injector cylinder 5 is faulty
  • ECM has failed
  • Faulty electrical connection

What causes the P0300 code?
  • Spark plugs that are damaged or worn
  • Spark plug wires and/or coils that are damaged or worn
  • Distributor cap that is damaged or worn (only if applicable to the vehicle)
  • Rotor button that is damaged or worn (only if applicable to the vehicle)
  • Fuel injectors that are defective
  • EGR valves or tubes that are clogged
  • Ignition timing that is off
  • Vaccum leaks
  • Fuel pressure that is low
  • Head gasket(s) that are leaking
  • Distributor cap that is cracked
  • Camshaft sensor that is faulty
  • Crankshaft sensor that is faulty
  • Mass air flow sensor that is faulty
  • Oxygen sensor that is faulty
  • Throttle position sensor that is faulty
  • Catalytic converter that is faulty
  • PCM is faulty

What causes the P0303 code?
  • Faulty spark plugs
  • Fuel injection issues
  • Plug wires, cap and rotor, or coil pack issues (depending on what vehicle is equipped with)
  • Mechanical engine issue
  • Intake air leaks

What causes the P0305 code?
  • The spark plug is not firing for cylinder number 5 due to fouling or cracks in insulation.
  • The ignition coil for cylinder number 5 has stopped firing.
  • The spark plug wire or plug boot is leaking ignition spark to ground for cylinder number 5.
  • The valve cover is leaking oil into the spark plug holes and shorting the spark plug firing for cylinder number 5.
 
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TexasTJ2K said:
I have a 2000 TJ, 4.0L, 5spd with the check engine light on. Sometimes, it will start blinking for a short time then return to solid again. Here are the codes I'm throwing:

P0205
P0300
P0303
P0305

So far, I've done the following: all new spark plugs, coil pack, cam shaft position sensor, and crank shaft position sensor. They've helped with the misfires but not gotten rid of them.
Also, there's an issue that I'm sure is being caused by these codes, but when the engine reaches operating temperature around 210, my engine will cut out after 3,000rpm. If I upshift it will start again, but when I hit 3k rpms the engine won't respond to anything. It doesn't shut off, but pumping the gas causes nothing and I am forced to shift.

Any help is greatly appreciated. Next up, I'm going to move around some of the injectors to see if the issue follows the injector or if it's something else. I was also told by a buddy who helps me with repairs that it could be the head gasket.

Thank you.
Click to expand...
How many miles are on it?

Possibly a stretched timing belt.
Head gasket is a possibility.
Have you done a compression test on it?
 
First and foremost, check the wiring harness very, very throughly for any signs of abrasion or wear that could be causing a fault.

Replace the spark plugs with the proper spark plugs (yes, these things only like specific spark plugs believe it or not), which you can find here: What are the best spark plugs for my Jeep Wrangler TJ 4.0?

If you end up replacing sensors (i.e. cam position sensor), you always, always, ALWAYS want to use an OE Mopar sensor, as any of the aftermarket brands you'll get at your auto part store WILL NOT fix the issue. This is a well known thing with TJs, so keep that in mind.

It's also worth noting that in the FSM there are procedures to test most of the sensors (i.e. CPS) with a digital multimeter. I would do that before replacing them. You can find the FSM here: Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation

So I think I would start with the spark plugs. What ones did you use, and what were they gapped too?
 
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Chris said:
First and foremost, check the wiring harness very, very throughly for any signs of abrasion or wear that could be causing a fault.

Replace the spark plugs with the proper spark plugs (yes, these things only like specific spark plugs believe it or not), which you can find here: What are the best spark plugs for my Jeep Wrangler TJ 4.0?

If you end up replacing sensors (i.e. cam position sensor), you always, always, ALWAYS want to use an OE Mopar sensor, as any of the aftermarket brands you'll get at your auto part store WILL NOT fix the issue. This is a well known thing with TJs, so keep that in mind.

It's also worth noting that in the FSM there are procedures to test most of the sensors (i.e. CPS) with a digital multimeter. I would do that before replacing them. You can find the FSM here: Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation

So I think I would start with the spark plugs. What ones did you use, and what were they gapped too?
Click to expand...

I did use Mopar brand sensors. I can't remember off the top of my head what spark plugs I have in there, if I remember correctly a local Jeep mechanic did it, I just sent him a text asking what brand he put in. The old invoice for the work just says "2002 Jeep spark plugs."
 
TexasTJ2K said:
I have a 2000 TJ, 4.0L, 5spd with the check engine light on. Sometimes, it will start blinking for a short time then return to solid again. Here are the codes I'm throwing:

P0205
P0300
P0303
P0305

So far, I've done the following: all new spark plugs, coil pack, cam shaft position sensor, and crank shaft position sensor. They've helped with the misfires but not gotten rid of them.
Also, there's an issue that I'm sure is being caused by these codes, but when the engine reaches operating temperature around 210, my engine will cut out after 3,000rpm. If I upshift it will start again, but when I hit 3k rpms the engine won't respond to anything. It doesn't shut off, but pumping the gas causes nothing and I am forced to shift.

Any help is greatly appreciated. Next up, I'm going to move around some of the injectors to see if the issue follows the injector or if it's something else. I was also told by a buddy who helps me with repairs that it could be the head gasket.

Thank you.
Click to expand...

OK - So, I'm just looking for a common denominator... All of the 300 codes are related to misfires. 300 is a general misfire in multiple cylinders, 303 means specifically cylinder 3 and 305 means specifically cylinder 5. P0205 seems to generically mean that there was fault detected in fuel injector 5, could be wiring, or the injector itself. My thought is that whatever is causing the 205 code is also triggering the 305 code at least. The 300 code could just be triggered because there are errors existing in both cylinder 3 and 5.

Given this, I would put my attention on cylinders 3 and 5. It might be worth noting that these two cylinders fire in sequence (1-5-3-6-2-4), so something going wrong in cylinder 5 might actually be triggering the error in cylinder 3. Based on that, I'd look at cylinder 5 first and foremost. Like others have mentioned, look over all the wiring closely. While you're in there take a close look at the ground wire from the battery. More than once, on many types of cars, I have seen or heard of a poor ground connection causing a host of bizarre issues.

You've pretty much covered all the ignition related items, so maybe look at injector 5 next. Moving them around isn't a bad idea. The simple act of unplugging moving and replugging items may be all that is needed to get some crud off a connector and clear things up. Or if the problem moves with the injector, you'll have your culprit. If it stays on cylinder 5, then maybe it is time to start looking deeper into the engine, starting with that cylinder.

But I am guessing that one pretty basic problem is causing multiple errors and making this seem worse than it is. <fingers crossed>

Please let us know how this goes. Good chance for us all to pick up some tips. I hate when these hard to track issues come up. Can be a real headache.
 
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Yeah, for those set of codes, I'd definitely be checking injector #5 first (check harness connector and then replace injector if necessary). This is the best place to start, in addition to making sure you have the right plugs like Chris said.

Also, there is a TSB for adding insulation on early Wrangler models to fix misfires in cylinder #3 (see attached). I'd give that a look since you have a 2000 model and are getting misfires in cylinder #3. It may not be the cause now, but I'd get 'er done if it hasn't been.
 

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  • tsb_1803103.pdf
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*Update*

CEL gone! Me and a buddy swapped and cleaned the 2 injectors on the misfiring cylinders. We learned that the injector that was originally on cylinder 5 was faulty. After replacing it, the check engine light went away and it passed inspection! Thanks so much for everyone's help.
 
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mots said:
Yeah, for those set of codes, I'd definitely be checking injector #5 first (check harness connector and then replace injector if necessary). This is the best place to start, in addition to making sure you have the right plugs like Chris said.

Also, there is a TSB for adding insulation on early Wrangler models to fix misfires in cylinder #3 (see attached). I'd give that a look since you have a 2000 model and are getting misfires in cylinder #3. It may not be the cause now, but I'd get 'er done if it hasn't been.
Click to expand...
My '02 has a heat shield (just looks like pieces of tin foil now) in this spot. Guy who worked at Chrysler told me it was a recall because of engine heat melting the fuel injector wires.
 
Chris said:
First and foremost, check the wiring harness very, very throughly for any signs of abrasion or wear that could be causing a fault.

Replace the spark plugs with the proper spark plugs (yes, these things only like specific spark plugs believe it or not), which you can find here: What are the best spark plugs for my Jeep Wrangler TJ 4.0?

If you end up replacing sensors (i.e. cam position sensor), you always, always, ALWAYS want to use an OE Mopar sensor, as any of the aftermarket brands you'll get at your auto part store WILL NOT fix the issue. This is a well known thing with TJs, so keep that in mind.

It's also worth noting that in the FSM there are procedures to test most of the sensors (i.e. CPS) with a digital multimeter. I would do that before replacing them. You can find the FSM here: Jeep Wrangler TJ Factory Service Manuals (FSM) & Technical Documentation

So I think I would start with the spark plugs. What ones did you use, and what were they gapped too?
Click to expand...
Spark plugs can cause a 0205? So if a plug isn't working for whatever reason, could that cause the PCM driver for that cylinder to not send the signal to the injector?
 
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justfixedthat... said:
My '02 has a heat shield (just looks like pieces of tin foil now) in this spot. Guy who worked at Chrysler told me it was a recall because of engine heat melting the fuel injector wires.
Click to expand...
I don't think there was an actual recall on this issue, but I could be wrong. I believe it was only the TSB that was issued (PDF attachment I posted). This is why we often see folks on here with TJs from that production range that haven't had it addressed before. Per the TSB, the cause is fuel being vaporized during heatsoak that causes the misfires in #3. It doesn't mention that the wires can be melted etc., but perhaps that is possible in extreme cases. I have not heard of it being that nasty before.
 
justfixedthat... said:
Spark plugs can cause a 0205? So if a plug isn't working for whatever reason, could that cause the PCM driver for that cylinder to not send the signal to the injector?
Click to expand...
No. P0205 is "Cylinder 5 Injector Circuit Malfunction". The PCM should not be looking at the spark plugs in any way to pop this code. It senses a problem with the #5 injector circuit, just like it says.

The most common causes for this code include:
  • Corroded fuel injector, connections or wiring
  • Poor or broken electrical connections in the connector or harness
  • Open or short wiring harness for the cylinder 5 injector circuit
  • Defective fuel injector power circuits
Clean up the injector 5 connector with electrical parts cleaner. Make sure the connection is good. Check the wires back from the #5 injector o the harness for continuity. Check the fuel injector for soundness (check resistance with a multi-meter).
 
mots said:
No. P0205 is "Cylinder 5 Injector Circuit Malfunction". The PCM should not be looking at the spark plugs in any way to pop this code. It senses a problem with the #5 injector circuit, just like it says.

The most common causes for this code include:
  • Corroded fuel injector, connections or wiring
  • Poor or broken electrical connections in the connector or harness
  • Open or short wiring harness for the cylinder 5 injector circuit
  • Defective fuel injector power circuits
Clean up the injector 5 connector with electrical parts cleaner. Make sure the connection is good. Check the wires back from the #5 injector o the harness for continuity. Check the fuel injector for soundness (check resistance with a multi-meter).
Click to expand...
Well the wires have perfect continuity. There are no grounds, testing all the back from the PCM to the injector. I replaced one of the pigtails (5 and 6 are giving codes) but it didn't affect anything, so it wasn't the injector plug itself. And I replaced both injectors with no change so it's not the injectors either.

I'd like to point out that #4 isn't firing either, but it's not giving codes.

Also, originally it was only giving 0206. I had swapped the #5 and 6 connectors to see if it was the connector or the injector itself, but instead it started giving codes for #5 and 6.
 
justfixedthat... said:
Well the wires have perfect continuity. There are no grounds, testing all the back from the PCM to the injector. I replaced one of the pigtails (5 and 6 are giving codes) but it didn't affect anything, so it wasn't the injector plug itself. And I replaced both injectors with no change so it's not the injectors either.

I'd like to point out that #4 isn't firing either, but it's not giving codes.

Also, originally it was only giving 0206. I had swapped the #5 and 6 connectors to see if it was the connector or the injector itself, but instead it started giving codes for #5 and 6.
Click to expand...
Sounds like a tricky one, it's tough that the problem duplicated and didn't follow like you had hoped. But yeah, at the end of the day, the codes mean what they mean from the PCM's perspective. In this case, if the wiring, connector and injector are indeed good, then my next guess would be an internal PCM circuit issue.

Another thought...not sure if it has merit or not. The connector for injector #6 could be damaged and caused a second circuit fault in the PCM when you plugged it into #5. I would not think this is very likely or common that this happens, but perhaps it is possible if the wires were fused.

P.S. If #4 is also not firing, but not giving any codes, something very odd is going one and I start leaning more towards the PCM.
 
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