Aaron75

My vehicles has 79k miles it’s a 350 CDI blue efficiency face lift version. I have it serviced regular and do long journeys. At last service I had oil breather and pipe and seals replaced and had the Intercoolerpressure checked and cleaned, to give longevity to EGR, Turbo and prevent oil / soot build up in Inlet pipes. I had noticed it go into limp prior to doing this, but it was an isolated incident. No check lights etc.

However recently whilst on long journeys I noticed that I lose boost but I manage to keep the car above 2500 revs to keep momentum up to stop me going at a snails pace from going into limp mode. As soon as it drops to 60/70 mph you’re stuck at no boost, until switch off and on. The car drives fine around town it intermittently goes into limp mode but ive never had CEL check light, the car resets itself or via switch off then on.

Read codes on a Snap On Solus Ultra

Engine Codes

2359 Charge pressure control. Too low boost pressure

2385 EGR control. Mass Air too large

2696 Check component B60/1 (Left exhaust back pressure sensor) Control variation - The exhaust back pressure too high


DPF Menu Live Data

RPM idle 700

Ash content 6

Soot content of DPF. 77.6

Distance driven single last regen. 181

B60 Exhaust back pressure sensor
HPA 1238

B28/12 Left Pressure Differential sensor DPF
HPA 800

B28/13 Right Pressure Differential sensor DPF
HPA 15

B28/8 Pressure differential sensor DPF
HPA 15


I’m guessing the charge pressure low boost and EGR Mass Air flowdeviationis are triggered by the faulty high back pressure sensor fault.

It’s clear to see the Left pressure sensor is reading very high, 800

I want to know if it’s faulty sensor and where exactly is it located ? Is it on Left bank manifold ? All threads I’ve read mention one sensor in between Turbo / EGR and the second near DPF under transmission tunnel, but I can’t find any mention of a left and right pressure differential sensor ??? I’ve checked Merc parts catalogue and can only see the one that sits near Turbo and EGR and the one located near the DPF underneath the car.

The DPF soot seems high, the car did complete a regen 181 miles ago when I drove back from London yesterday, Ive read that DPF regen relies upon readings between the sensors being compared but a faulty sensor prevents regen,

I attempted the forced regen due to the 70 % plus build up of soot in DPF, but it kept failing to perform the regen, error locating signal.




I want a 2nd opinion pls, am I on right track focussing on the left pressure sensor ?

Is this preventing the car automatically completing the regen of DPF as well as the forced regen through the computer ?

Lastly are there two different left and right pressure differential sensors because I’m struggling to find their location.