Code P1026
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Intermediate
Joined: Nov 2019
Posts: 31
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Code P1026
Hey guys, I need some help with my Panamera. I posted about these issues before but didn't get any responses. Here's an update in case anyone has some ideas. My car is a 2011 Porsche Panamera 3.6L. Here are the issues:- The engine takes a long time to start.- The idle is rough.- The check engine light is on.- I get the message "Reduce Engine Power."- The Start/Stop feature is deactivated.- The codes P1031 and P1026 are showing up. I did some research and took it to a professional shop. They thought it could be the high-pressure fuel pump (HPFP), so I replaced it yesterday. I cleared the codes and started the car, but the same exact issues are still happening. The only difference is that now I'm only getting Code P1026 (no P1031). I thought it might be a voltage-related issue, so I just replaced the AGM battery under warranty today. I cleared the P1026 code and started the car again. Same thing happened - Code P1026, rough idle, check engine light, and reduced power. If I touch the gas, it seems to smooth out a bit, but it's still really rough when I first start the engine. I'm using the Foxwell Scan Tool to read and clear the codes. Any suggestions, ideas, or things I should check?
I greatly appreciate any help!!!!!
I greatly appreciate any help!!!!!
Advanced
Joined: Nov 2023
Posts: 89
Likes: 24
From: Stuttgart
First, check the fuel pressure sensor, fuel injectors, and fuel lines. Then, inspect the air intake system for leaks or blockages, including the air filter, throttle body, and intake manifold. Next, look for leaks or damage around the oxygen sensors and catalytic converter. Plus, check the timing belt and chain.
Thread Starter
Intermediate
Joined: Nov 2019
Posts: 31
Likes: 7
Thank you for the recommendations.
I believe that inspecting or replacing the fuel pressure sensor beneath the intake manifold could be a reasonable course of action.The P1026 code appears to be related to fuel-specific issues. Considering that I have already replaced the high-pressure fuel pump and cam plug, the remaining fuel-related components would be the pressure sensor under the intake and the low-pressure in-tank pump and filter.
As for air filters etc, I think that would be a gradual issue and not an overnight problem.
The car just turned 50k and have never had a single issue until this.
I believe that inspecting or replacing the fuel pressure sensor beneath the intake manifold could be a reasonable course of action.The P1026 code appears to be related to fuel-specific issues. Considering that I have already replaced the high-pressure fuel pump and cam plug, the remaining fuel-related components would be the pressure sensor under the intake and the low-pressure in-tank pump and filter.
As for air filters etc, I think that would be a gradual issue and not an overnight problem.
The car just turned 50k and have never had a single issue until this.
Intermediate
Joined: Mar 2011
Posts: 26
Likes: 2
Apparently, P1026 is "fuel pressure implausible."
That suggests to me that either you really do have below-spec pressure in the high pressure rail, or the sensor that monitors it is faulty.
You might find this useful:
https://rennlist.com/forums/cayenne-...1031-help.html
One of the things that thread mentions is that fuel pressure output of the high pressure pump is dependent on pressure output of the "pre-delivery" system - the pump, lines and filter that carry the fuel from the tank to the engine bay. What I would do is try to get some more data, first from the high pressure rail sensor, and then also from the low pressure system. There should be a spec for the pressure in the low pressure system - something like 30-50 PSI I'd guess. If that checks out, then you go after the high pressure system, but if it's low, and the high pressure system also has low pressure, then you can strongly suspect that your problem is on the low pressure side.
That suggests to me that either you really do have below-spec pressure in the high pressure rail, or the sensor that monitors it is faulty.
You might find this useful:
https://rennlist.com/forums/cayenne-...1031-help.html
One of the things that thread mentions is that fuel pressure output of the high pressure pump is dependent on pressure output of the "pre-delivery" system - the pump, lines and filter that carry the fuel from the tank to the engine bay. What I would do is try to get some more data, first from the high pressure rail sensor, and then also from the low pressure system. There should be a spec for the pressure in the low pressure system - something like 30-50 PSI I'd guess. If that checks out, then you go after the high pressure system, but if it's low, and the high pressure system also has low pressure, then you can strongly suspect that your problem is on the low pressure side.
Thread Starter
Intermediate
Joined: Nov 2019
Posts: 31
Likes: 7
So, I replaced the HPFP with an aftermarket remanned unit and purchased the plastic cam plug from Porsche.
This eliminated code P1031, but I still have code P1026 and same driving symptoms.
I decided to take it to a euro shop to have diagnostics performed. I told them I just replaced the HPFP with an aftermarket unit. They asked if I replaced the fuel pressure sensor which I did not.
After "testing", they said all their testing leads them back to the HPFP that I just replaced. Said they do not put on anything but factory new pumps. They said they can see spikes and dips in fuel pressure.
Quoted 2800 for pump, fuel pressure sensor & labor. Said they always replace the sensor when they replace the HPFP (thats not reassuring that they actually pinpointed the issue....more like lets make sure we cover all the basis with new parts while we are in there)
I'm more than capable of replacing the parts......but..
How do I know what they're saying is fact? Unfortunately its hard to trust anyone these days.
This eliminated code P1031, but I still have code P1026 and same driving symptoms.
I decided to take it to a euro shop to have diagnostics performed. I told them I just replaced the HPFP with an aftermarket unit. They asked if I replaced the fuel pressure sensor which I did not.
After "testing", they said all their testing leads them back to the HPFP that I just replaced. Said they do not put on anything but factory new pumps. They said they can see spikes and dips in fuel pressure.
Quoted 2800 for pump, fuel pressure sensor & labor. Said they always replace the sensor when they replace the HPFP (thats not reassuring that they actually pinpointed the issue....more like lets make sure we cover all the basis with new parts while we are in there)
I'm more than capable of replacing the parts......but..
How do I know what they're saying is fact? Unfortunately its hard to trust anyone these days.
