Exhaust flow reversal fault (some diesels with anti-shudder valve).
P2359 — also written P2359, P 2359, 2359 — is the OBD-II code for reversing exhaust flow fault. Same code, same fix: this page covers every spelling of it.
This one usually boils down to your anti-shudder valve failing to close or open when the ECU expects, common on VAG and Mercedes diesels where carbon buildup stops the flap dead.
P2359 is a emissions fault code, typically costing £150–£700 to put right in a UK garage.
What P2359 actually feels like to drive
- The car shakes like a wet dog for three seconds when you switch the engine off.
- Limp mode kicks in, often when you're coasting or coming to a stop at a roundabout.
- A noticeable 'whoosh' or 'hiss' sound from the intake when you lift off the throttle.
- Loss of power on the motorway, usually clearing itself after a 'key-off, key-on' reset.
- The engine feels like it's fighting itself during a DPF regeneration cycle.
What causes P2359?
- Failed anti-shudder valve
- Blocked EGR path
UK vehicles that throw P2359 most often
- VW Golf Mk6 2.0 TDi (CFGB/CFFB) 2009-2013
- Mercedes-Benz Sprinter 2.1 CDI (OM646/OM651) 2006-2016
- Audi A4 2.0 TDi (CAGA/CAGB) 2008-2015
- Mercedes E-Class E220/E250 CDI (W212) 2009-2014
- Skoda Octavia 1.6 TDi (CAYC) 2010-2013
- Seat Leon 2.0 TDi FR 2009-2012
How P2359 is fixed
- Replace anti-shudder valve
- EGR service
The P2359 misdiagnosis that wastes money
I've seen so many lads just fire a new EGR valve at this because it's the first thing they see on a scanner. They spend £250 on a Pierburg unit, swap it out, and the light's back on before they've even finished their brew. Most of the time, the EGR is actually fine; it’s the anti-shudder valve (or throttle body) that’s gummed up with thick carbon or the plastic gears inside have stripped. Don't go buying parts until you’ve physically checked if that butterfly valve is actually moving smoothly.
What a UK garage should charge for P2359
A basic diagnostic plug-in will cost you £50 to £90 depending on where you are in the UK. If it's just a carbon clean of the valve, expect an hour's labour (£60-£100). If the valve is toast, a genuine Bosch or VDO unit is usually £180-£300, plus another hour to fit. A Mercedes main dealer will easily rinse you for £700+, but a good independent should see you sorted for under £400 all-in.
P2359 repair cost in the UK
Most P2359 repairs land between £150–£700 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P2359
Before you let a garage sell you a new DPF or EGR, ask them to perform a 'throttle body adaptation' or 'alignment' via the diagnostic tool. If the valve can’t complete its sweep, the P2359 triggers. Also, ask them to check the wiring loom near the starter motor or gearbox—it’s a common spot for chafing on VWs and Mercs, which sends the ECU into a frenzy thinking the air flow has reversed when it's just a short to ground. If they won't show you the live data for the 'Commanded vs Actual' valve position, take your car elsewhere.
Can you drive with P2359?
Yes.
Urgency: medium.