LIMP MODE - code 0403 chrysler 300 2006
 

My car is a nightmare. Literally has been in and out the shop for the last 3 years.

My car would go into limp mode. It does not accelerate and feels likes its about to die but doesnt. I've changed my 02 sensor, throttle body, egr valve. and new pcm. The code i get is 0403. I brought it to the chrysler dealership and they just eyeballed the problem telling me its my egr value (no its not, **** you). I told them that the pcm is giving a lot more than one error code. they come back and tell me it is possible a bad pcm that i changed a little over a year ago.

It can possbily be a bad pcm bc i did buy it online. But i've done endless research and i think it maybe a bad catalytic converter? Please HELP! its a money pit!

I forgot i changed the crankshaft sensor and map sensor as well....

I fail to mention it happens more frequently during the summer. DUring the winter it runs normal...weird...

ok mmm limp in mode if for the transmission nothing to do with the engine .
With all of what u have said U have replaced still dont know what u are asking what are some codes and who changed all this stuff out?

"Limp mode" = rough idle, cannot accelerate. What i'm asking is what other possibility can be wrong with the symtoms my car is having....

Chyrsler changed few of the parts and a local mechanic shop did the rest.

ok wrong terminology then limp in mode is for the transmission only when its in second gear there is not any sorts of mode for an engine. What are you currant codes in the computer?

Get hold of a 30,000 microfarad capacitor of at least 16volt working, and wire it temporarily with clips across the battery. This will be an electrolytic capacitor which is polarized and therefore will need to be wired across the battery the right way round, +ve. to battery +ve. etc.
You can get these at radio/electronics shops, or maybe find one in an old computer power supply. The capacitance is not critical but the voltage musn't be less than 16volt. Even if you have to pay for it, you're looking at a few dollars at most.

If it works, wire a 10amp. slo-blo fuse in series with the +ve. lead and install it properly so it doesn't flop about.

Oh, and report back if it does work. No guarantees of course.

Leedsman.

Leedman are u Fing serious? What in gods green earth are u talking about it has ZERO info to contribute to this post I have seen all your others ones as well its its simply adding fluff to cotton candy.

I'm not quite sure what "Chrysler-Tech" means by the expression 'Fing serious', HOWEVER---

I had constant problems with the MIL lamp coming on and "restricted performance" shown in the window of my previous car, an S-Type diesel Jag. It could do it anytime anywhere. That car also had a number of micros controlling such as engine, transmission etc. just like my current Chrysler.

Having much experience with microprocessor-controlled machinery, I knew a micro controller is only as good as its power supply. Our statistics at ADT showed over 50% of control faults for muxs., panners, lenses etc. turned out to be the power supply to the controlling micro. Usually, an electrolytic capacitor had gone dry and wasn't working properly, leaving switch-mode "hash" on a power line. (This was a stock fault on a certain Panasonic video recorder -- famously).

The power supply to ALL the micros in a car is, guess what, ---

THE BATTERY.

After installing the 30,0000 microfarad capacitor on the Jag's battery, the problem stopped, and stayed that way for the next three years until I got shot of the car.

Explanation:--

Lead-acid batteries are known to "resonate", more so as they age through the service life. This resonance is held to be anywhere between 2 and 6MHz. Now it just so happens that the clocking frequency of many micros usually lies in that bandwidth. Lead-acid batteries have a very low internal resistance indeed, say .01 ohm, but a battery IMPEDANCE (like a/c resistance) can be very different, esp. as it ages. This can aggravate the situation. A 30,000 microfarad capacitor wired across the battery will drop the impedance of the battery to near zero. In fact I went the whole hog and wired a small tantalum capacitor as well just to make sure the battery impedance was as low as poss. (Tantalums have no ESR, Effective Series Resistance).
Each micro in the car often has more than one clock Indeed the home computer I'm using now will have at least six. So it's just not possible to know EXACTLY what's going on when there's a fault, it's all trial and error in this instance of trouble-shooting.

So this resonance can upset micros. The answer could be a new battery at £150 or so, or would you prefer a few dollars for a capacitor to do the same job? Whatever, it costs so little to at least try that avenue, and the OP seemed to be getting desperate, and I felt a little sorry for him and the troubles he's having with his Chrysler. However, I'm the first to say there's no guarantee. Even the car manufacturers can have their control micro problems, famously Toyota with sudden uncontrolled acceleration in some of their cars.

One would hope that this explanation helps, Mr. Chrysler Tech., but one does appreciate that electronics can be difficult and counter intuitive to someone not so inclined.

Leedsman.

first this is not a jag or a diesel or a UK spec car
The systems u are talking about are way different then ones you will find on any shelf in a store.

This guy is complaining about a rough idle not a battery issue nor a battery drain the battery theory u have described in such detail is irrelevant in this matter. Battery drop or frequency is then again irrelevant in a cars issue. Why because the alternator is charging up the battery and running the whole car. The voltage will change based off the currant needs of the car so they are ever changing and FYI u are comparing apples to oranges in the power supply. Home computer use AC currant with a steady 110 or 220 vol source it must be the same. Cars use alternator which makes ac and converter it to DC and it will change from 13 volts to 14.4 volts and 50 to 110 amps depending on the car. And Chrysler cars the slowest Clock speed was 14mhz if i remember right old technology the new cars use up to 600mhz data buses so your 2-6 mhz frequency deal is once again irrelevant. Also the engineers that design the cars kinda know how this system works they designed it know know about frequency and latent heat and all of the wonderfully items of and engineer. A battery used on a Chrysler serves two proposes one starting power to get the car running.
Second a charging post for power from the alternator and a buffer for any voltage spikes that's it U can remove the battery and the car will still run.