P0300 03 Grand Caravan with the 3.8

[dagr8tim]

I actually have 4 codes (P0135, P0300, P0442, P0455), but this is the first one I want to fix because of the risk of damage to the engine.

P0135 is the upstream 02 sensor, it's heated to most of the time the heating element has gone out.
P0300 is a random misfire.
P0442 & P0455 are a small and large EVAP leak, which commonly seems to be the connector hoses to the purge selnoid.

It was too dark once the van cooled down to poke around. The wires looked good, I'm going to check them closer tomorrow and pull the front side plugs to get an idea of their age and condition.

The short list for the P0300 is:
- Faulty spark plugs or wires
- Faulty coil (pack)
- Faulty oxygen sensor(s)
- Faulty fuel injector(s)
- Burned exhaust valve
- Faulty catalytic converter(s)
- Stuck/blocked EGR valve / passages
- Faulty camshaft position sensor
- Defective computer

Anyone got an idea where to start troubleshooting without just randomly throwing parts at it? Could the O2 sensor from P0135 be causing the misfire? What about unmetered air getting into the intake from the EVAP leak causing a lean condition? I've got alittle extra money that I can afford to fix this right. I just don't want to waste money on things that are not bad, because that cuts into my Jeep budget.

[Steveakus]

fix the upstream o2 sensor first

make sure there is no intake, exhaust or vacuum leaks

the upstream o2 sensor needs to be your primary concern, can and will cause the other 2 issues depending on the problem with it


EDIT - does it only do this after driving for a while ?? Catalytic Converter Possibly choking off ?

[dagr8tim]

fix the upstream o2 sensor first

make sure there is no intake, exhaust or vacuum leaks

the upstream o2 sensor needs to be your primary concern, can and will cause the other 2 issues depending on the problem with it


EDIT - does it only do this after driving for a while ?? Catalytic Converter Possibly choking off ?

I pulled the negative battery terminal and left the doors open for about 5 minutes. After that, I started it up and let it idle in the driveway for 5 minutes, then took it on a 2 -3 mile drive. I couldn't get the CEL to pop, and based on what I was seeing in Torque with my OBDII to Bluetooth adapter, I should have hit closed loop. I'll keep an eye on it tomorrow and see if/when it comes on.

I'll probably order the 02 from Rock Auto this week. What sucks is the easiest way to get at the 02 is to pull the wiper tray. That's also the easiest way to go to the spark plugs on the back side.

[smccollamjr]

If an 03 is the same as an 06 you can get to the rear plugs and upper o2 without removing the wipers but it's a pain. Also, the cat has an 80k mile warranty so if you're close get it checked. Mine went at 90k, but probably started plugging off long before that.

[dagr8tim]

If an 03 is the same as an 06 you can get to the rear plugs and upper o2 without removing the wipers but it's a pain. Also, the cat has an 80k mile warranty so if you're close get it checked. Mine went at 90k, but probably started plugging off long before that.

I'm at nearly 131K.

Any tricks for getting at the far side of the engine without removing the wipers?

[smccollamjr]

Small hands and remove the PCV valve.

[Steveakus]

Probably the main reason you werent seeing normal Lambda after removing the battery is because after unhooking and cap draining modules they usually take about 10 full drive cycles to adjust/relearn all the sensors

[dagr8tim]

Probably the main reason you werent seeing normal Lambda after removing the battery is because after unhooking and cap draining modules they usually take about 10 full drive cycles to adjust/relearn all the sensors

Cool. At this point I'm going to monitor it and keep my little Bluetooth adapter hooked up to monitor the situation. It also looks like alot of EVAP leak codes on this van come off the purge solenoid where there are some short sections of soft line to take up vibrations and they tend to wear/rub holes in them.

Thanks for all of your help.

[watch out]

dont forget the fuel filter, if it has one, most ramdon misfire codes are fuel related, so make sure you ck your fuel filter.