2.0HDI Revs out of control and high idle

Discuss, ask, or get help with engine and mechanical queries in here.

Moderator: Moderators

Post Reply
User avatar
Klinto75m
1.6 8v
Posts: 12
Joined: Tue Feb 09, 2021 9:05 pm
Location: Denmark

2.0HDI Revs out of control and high idle

Post by Klinto75m »

Hey,

I'm having a bit of trouble with the car. This has been an ongoing issue for the last year or so. The car is fully driveable and such, but now that it has been colder, the issue starts to appear much more noticeable.

Model: 406 2.0HDI 110
Year: 2001
Motorcode: RHZ
Note: Fitted with a 1999 BSI and ECU

When driving the revs would randomly "spike" revving up and staying for 1-2 seconds before going low again. This could also be, that I removed my foot from the speeder, and the car would hold the revs without going back to normal before I slow down.
Now that it is cold it runs high idle around 1200-1300rpm going up and down a bit. When I do a cold start, it's also very easy to stall. This means I can't get the car moving without giving it some gas.

After reading the faults, the following keeps coming back:
- P0402 EGR-valve, positive deviation
- P0221 Throttle/position sensor; compliance between wire 1 and 2
(Those are translated to my best)

I have a spare Throttlebody which I've swapped with no effect. When opened I can't see anything wrong, but might not know what to look for.

The EGR valve "should" be clean, after haven got a "HyDrive" last year, which is cleaning out the exhaust system with hydrogen.
But to be sure I'm planning to remove it, and cleaning it with some EGR Cleaner. Is there a way to test it, to make sure it's opening and closing alright?
(2018-2021) Peugeot 406 st. - 2.0HDi RHZ - 2001
(2021 - ) Peugeot 406 st. - 2.0HDi RHS - 2002
PeterN
3.0 24v
Posts: 1673
Joined: Sun Mar 04, 2012 6:04 pm
Location: Charmouth, Dorset

Re: 2.0HDI Revs out of control and high idle

Post by PeterN »

Just a thought but you haven't got air in your fuel line have you, that can do things similar to that. Fit a clear section of plastic pipe in the input line to the filter and check for bubbles.

Peter
User avatar
Klinto75m
1.6 8v
Posts: 12
Joined: Tue Feb 09, 2021 9:05 pm
Location: Denmark

Re: 2.0HDI Revs out of control and high idle

Post by Klinto75m »

Sorry for the late response. Can air in the fuel line provoke the same behavior?
Example on my issue:
Going around 60km/h in 4th gear.
RPM is around 1600
Press the clutch
RPM goes up to 2100
after about 5 seconds, it will drop to around 1k.

I Will try to get a reading out with the tester, so it's easier to understand.
(2018-2021) Peugeot 406 st. - 2.0HDi RHZ - 2001
(2021 - ) Peugeot 406 st. - 2.0HDi RHS - 2002
User avatar
steve_earwig
Moderator
Posts: 19798
Joined: Thu Oct 04, 2007 6:09 pm
Location: Jastrebarsko, Croatia http://www.jastrebarsko.hr/lokacija/

Re: 2.0HDI Revs out of control and high idle

Post by steve_earwig »

Might be the clutch switch borked? Hmm, that'll give a high idle at rest but not sure about at speed.
Unskilled meddling sin©e 2007

The submitted form was invalid. Try submitting again.
Scottyscoob
Newbie
Posts: 1
Joined: Fri Nov 26, 2021 9:40 pm

Re: 2.0HDI Revs out of control and high idle

Post by Scottyscoob »

My car is having exact same issue, did you end up managing to fix this?
406pug
Newbie
Posts: 3
Joined: Wed Mar 23, 2022 7:23 pm

Re: 2.0HDI Revs out of control and high idle

Post by 406pug »

I'm having exactly the same issue too - did anyone find a solution?
Post Reply