Help Needed P1298 Fault code

[Gb53]

Hi, I'm new to the forum (& forums in general) & need help with a problem.

My Nw GLXR, bought new ,and used mainly for towing. it's done 101,000ks, no mods apart from extra fuel filter. Van is 2.5 tonne loaded & hasn't caused any problems in the time we've had the car.

We were going from Tamworth to Armidale & up a steep climb when the CEL came on . No obvious faults so continued slowly to Armidale. Car drove ok but was little down on power.

Dealer checked it the next day & code was P1298 VGT. Cleared the code & tested car (without van), also checked all vacuum hoses etc for leak/splits. suggested that steep climbs towing heavy loads can trigger this fault & that if it happened again would need to replace VGT solenoid, at approx $450 (part) plus labour only OEM part in Aus in Melb & 5 days to get!!! No problems from Armidale to Sunshine coast.

Always been serviced on time last one was 105K service. Mechanic said lower inlet manifold looked ok, maybe get it cleaned next big service.

Suggestions online seem to be:
(1) Check/replace hoses for MAP sensor & all lines to do with VGT solenoid.

(2) Fit a Dawes valve to help control boost.

(3) Replace VGT solenoid

Which of these would work best Or which combo

Does anyone know of a GOOD mechanic with experience in Pajy's on the Sunshine Coast. will be here till mid September.

Thanks.

[nj swb]

You're not driving a Patrol. There are thousands of these Pajeros towing vans like yours around the country without needing a Dawes valve.

Start with 1).

I would've expected that operation of the VGT would be testable with a MUT3 - did the dealer do this? If that can't be done / is inconclusive, then consider pulling the VGT solenoid and checking its operation / if the vanes are moving freely / smoothly. If there is a problem that can't be fixed, replace the VGT.

If you really want a Dawes valve, fit one. I don't believe it will hurt.

[BruceandBobbi]

P1298 is overbost.

(1) Check/replace hoses for MAP sensor & all lines to do with VGT solenoid. The dealer should be able to check the resistance of the MAP.

(2) Fit a Dawes valve to help control boost. Very hit and miss. Been there done that.

(3) Replace VGT solenoid. Dealer should be able to test if solenoid is holding a vacuum.

I think with vacuum leaks you would have P1299 code which is under boost.

Haven't heard of steep climbs towing a van could cause ir. There are much more knowledgeable people here than me that let me know if I'm incorrect.

Lucky for you there are no more climbs to the Gold Coast after Moonbi. I wouldn't like your chances of coming up Cunninghams Gap.

[CERadventures]

May or may not be related, but whilst chasing a similar condition of the vgt I found I needed to lubricate the vacuum activator shaft a little to ensue a smooth travel. May help?

[Gb53]

Thanks guys,
Believe the dealer did test with Mut3, mechanic seemed to be prepared to do more than just says "computer says no". Now 500ks from that dealer so can't easily talk to him. I had the impression that the particular road with its really long steep climb may have caused same issue with other pajy's.
Will spend a bit of time checking what I can while I'm camped. Limited tools & old/stuffed body will mean only basic stuff.

Thanks

[PaulMcG]

That climb up the range leaving Tamworth heading north, (not sure what it's called, a local will know), is a pretty severe test of any vehicle towing a 2.5t van. It's by far the steepest, longest, most sustained climb I would think most caravans would undertake. I towed a similar load up there last year with our Gen 4, and while I didn't get any codes, it's certainly the hardest my vehicle has ever worked.

Since your vehicle sounds like it's gone OK towing from Armidale onwards, and the dealer couldn't replicate the fault (even though without towing), I would be inclined to think you should be OK to go with their diagnosis. It sounds like you have a well maintained vehicle, so maybe just monitor things during your time on Sunshine Coast, and try a couple of more scenic climbs up the range in the hinterland. (The Hunchy to Montville climb is steep, also coming up the western side of the range from the Obi Obi/ Kenilworth area back towards Mapleton Falls would be a pretty good test- nice drive, too.)

[BruceandBobbi]

Moonbi Range.

Not a local and never towed up there but traveled it many, many times in our Pajero. Yes its long and hard.

[Gb53]

Thanks Paul,
Checked all the solenoid & map sensor hose no leaks & all in good condition. Map sensor port into manifold is clear. Can make the vacuum activator shaft move by sucking on vac hose so it's moving freely.
Hoping it was just the long steep climb that made it have a "hissy" fit. Will do some more stuff when we get back to Victoria (not looking forward to that).

[Uncle Fester]

Did you find out what the cause was?

[Davo134]

Hi Gb53,
I have a NW and when towing on a incline my paj does the same goes into limp mode engine lamp comes on,this was 2 years ago roughly before covid mm dealer replaced solenoid on turbo as it was overboosting,great thought it was fixed recently had 5 days away towing 2.5 t van same thing happened going up an incline .so lots of good advice on this forum im still in the process of elimination on lots of ideas and suggestions .Good Luck

[Uncle Fester]

Does anyone know what the cause was?

[HAYDOPOTATO]

hi did you guys get a fix for this?

[redbruce]

hi did you guys get a fix for this?

Gb53 last post was 30/01/22 so may have left the room.

Do you have overboost or underboost?

Post #3 covers overboost.

Common causes of underboost are inlet leaks (intercooler and hoses), blocked/faulty MAP and uncommon causes are faulty VGT (vac leak, acctuator, linkages), faulty EGR, and restrictive air filter element.