HELP Jeep CRD No Boost P1202

esb12510 · **Posted:** Wed Jul 08, 2015 8:45 am

I have an 05 CRD that is having issues with P1202. I've been doing endless research on this code and have found that in general, it is caused by air in the fuel causing a stuck regulator. I really would like some input before starting on my checklist of things to inspect. First of all, the engine was from a donor vehicle that was rolled. The engine was put in about 300 miles ago and have had this problem since install. There doesn't seem to be anymore oil lying around in the engine from being rolled (no smoke), but it's hard to tell if there are still deposits around. Not sure if that is relative to the problem or not.

Secondly, I'm constantly purging air from the filter head (especially after leaving it sit for a few hours). The filter is new and there are no visible cracks in the head. I had initially thought the culprit was the connections on the tank itself, so I dropped the tank and replaced with new hose and hose clamps. Still same issue.

Here's the confusing part:
When I first start the Jeep, it never struggles (even if I haven't bled air out of the filter head) and I have a CEL for P1202. I have an OBDII scanner and have tried both clearing and not clearing the code.
Clearing P1202- NO ISSUES AT ALL (and the CEL does not come back on during the entire trip until shut off again)
NOT clearing P1202- Loss of power (can have my foot to the floor and it revs up to 3 grand and eventually shifts, loss of boost, really struggles uphill)
If I shut the Jeep off after driving with the code cleared, the code reappears and I experience the same loss of power. If I have the Jeep running and pull off, clear code, power is restored.

So in short, the symptoms only appear when the actual code is being recognized, and it seems to cut fuel (or recognize there's air in the fuel?) and therefore limit boost.

I'm going to continue checking for air (seeing if the low pressure lines have air or not) but would appreciate some advice from you guys that may be more familiar with these engines. So much computer control on these. :shock:

I currently do NOT have a lift pump but am strongly considering one. With that being said, I hate to start replacing parts and not see this annoying symptom go away.

flash7210 · **Posted:** Wed Jul 08, 2015 10:24 am

This is not a turbo boost problem. Its fuel rail pressure/injector problem.
The code is throwing the ECM into limp mode with reduced acceleration making it feel like a lack of power or no boost.

I believe this code points specifically to injector #2.
Try unplugging all four injectors and firmly plugging them back in again.

edit:
P1202 - FUEL SYSTEM OVER-PRESSURE - Stuck Regulator (Diesel)

geordi · **Posted:** Wed Jul 08, 2015 1:11 pm

Credit to MrMopar64 for this information:

This fault is caused when the rail pressure is too high and either the metering unit (on the pump) or the pressure control valve (on the rail) is being commanded to the fully closed position.

The fault can be caused if: the metering unit is stuck open, the pressure control valve is stuck shut, or if you have a lift pump, the pressure being supplied is too high.

The metering unit can be replaced separately. The pressure control valve can be replaced separately, but MUST be replaced if you remove it from the rail at all. It has a one-time-use seal on the solenoid that cannot be repaired.

esb12510 · **Posted:** Wed Jul 08, 2015 2:05 pm

So I just unplugged and reseated all the connections to the injectors. Still showing the code with restart. I'll need to look into the metering unit and pressure control valve. The only doubt I have with that theory is that without the code it's completely fine. Could the ECM be forcing either one into the stuck open or stuck closed position because it senses air in the fuel? I'm trying to figure this all out.

flash7210 · **Posted:** Wed Jul 08, 2015 3:00 pm

You are gonna have to fix the air in fuel problem before doing anything else.

SargeIndustries · **Posted:** Wed Jul 08, 2015 3:12 pm

Make sure the plug on the back of the high pressure fuel pump is plugged in. Last time I had mine apart I forgot to plug it in thinking it was the Air Control Valve Plug (which was removed from the vehicle).

papaindigo · **Posted:** Wed Jul 08, 2015 3:55 pm

Now is the time to apply the KISS principle or Occam's razor and, as flash7210 says, tackle the known problem that could also cause your code problem. That's your comment that you have to constantly purge air from the fuel filter head. So:
1. do you have the 1s or 2n gen filter head. If there is a blue electric plug on the driver side you have 2n gen. If you have 1s gen stop right there and order/install a new 2n gen filter head with new blue fuel heating plug and go from there
2. did the problem start after you installed that new filter? If yes remove that filter and check to see if you left on the inner gasket (one on post the filter screws onto). That's a known air in fuel source.
3. pump the primer until hard then take a dry paper towel and feel all around the filter head, filter base, WIF sensor on bottom of filter, both electrical plugs, shaft of primer pump, and bleeder for any fuel leaks which will cause air in fuel. Paper towel getting wet with fuel is a dead giveaway for a fuel leak.
4. are you bleeding the head properly - see Sir Sam's video on the NOOB guide. Ideally use a bit of clear vinyl hose on bleeder leading to a catch can to keep from dripping fuel. Pump primer until hard, crack bleeder, when air/fuel stops coming out tighten bleeder. If you are cracking the bleeder and leaving it open while pumping primer all you are doing is recycling air.

If you replaced both quick disconnects on the fuel supply line back by the tank with hose (hopefully good diesel rated fuel hose not hardware store junk) and clamps and you fuel tank is reasonably full then any air source would be at or forward of where the supply hose connects the filter head. I suspect a problem at the filter head itself.

esb12510 · **Posted:** Wed Jul 08, 2015 5:43 pm

Update:
So with all your suggestions, I figured I'd start at the filter unit to try to find the issue since it's the easiest to access. I do have the old style filter head installed right now to hold me over because I accidentally put a crack in the 2nd gen trying to install it initially after the swap (oops), so another 2nd gen one is on order. The filter itself is brand new and was installed by my mechanic so I figured that it wouldn't be the problem. However, I wanted to be sure so I took filter off anyways and thanks to papaindigo, I immediately saw that the inner gasket was still on. So, I removed it, cleaned the entire unit up, purged all of the air out of the system, and took it for a drive. The code is still coming on, but I definitely noticed a performance difference. It still isn't perfect, but I feel as if that gasket was definitely allowing air to enter the system. I went up a steep incline and could maintain speed (still not gain, but still an improvement from losing 20 mph by the time I'm at the top). I came home, bled just one turn of air out of the filter until I got pure fuel, then left again and repeated. I did still try to clear the codes and the jeep runs like it should when the code isn't being recognized. Am thinking maybe I'll just run it a while and see if the air works itself out of the system and keep an eye on how much I purge out of the head.

So I guess I still have a couple of questions:

The heater plug is not plugged in (because I have the 2nd gen wiring harness and the 1st gen filter head so the connector doesn't fit), could this "open" connection be a source of air? Therefore, do you think simply replacing the entire unit would possibly be the cure for the problem itself (were the 1st gen heads REALLY bad with sucking air?)

If you don't think this filter head would be the prime problem, what else should I check (both lines coming off the filter were full of fuel, didn't see any air but they also aren't clear so it's hard to tell)? I believe the high pressure pump connector is hooked up (as suggested by sargeindustries).

Thank you guys SO MUCH so far. Am already feeling better about the situation. :BANANA:

papaindigo · **Posted:** Wed Jul 08, 2015 7:21 pm

Just to be clear there is supposed to be an inner gasket on the filter where it screws onto the post but there are not supposed to be 2 of them - the old one and the new one. If you found 2 and removed one that's a likely source of air.

The 1s gen head was not "bad" about sucking air UNLESS the fuel heater element got fried which was likely as it was too small. I can say from personal experience with a 1s gen head/burned element/air problems that an air leak in that plug, open or closed, may not be visible. I had no apparent leak but if I stuck a dry "Q" tip in the heater element plug hole and took a whiff of the "Q" tip afterwards if smelled of diesel fuel.

The only way to see fuel flow thru the lines is to either temporarily add a bit of clear vinyl hose to both lines or install a clear glass filter in the lines. I'd not bother until you get a 2n gen head installed and see if it cures your problem.

esb12510 · **Posted:** Wed Jul 08, 2015 9:13 pm

I'm hoping the new filter head is enough to fix the problem but it's hard to say. I'll update after it arrives and has been installed. Thanks for your help so far!

geordi · **Posted:** Wed Jul 08, 2015 9:22 pm

Did you have two of the center gaskets on the fuel filter, or just one? The correct way is just one, obviously.

esb12510 · **Posted:** Wed Jul 08, 2015 9:29 pm

There was just one. So I just went out and put it back on after you clarified there should still be ONE just not two. Lol. :-)r

Maybe the improved performance was because the air is being worked out with more driving and priming? Hard to tell.

danos_007 · **Posted:** Thu Feb 07, 2019 8:43 pm

Any one resolve this? I’m getting the p1202 code after the engine goes above 3000 rpm. It won’t set the code on idle or lower Rpms.

HELP Jeep CRD No Boost P1202

Who is online