A 2015 Peugeot Partner rolled into a Swedish workshop recently with a hard start condition and two seemingly unrelated fault codes logged in the system. The scan showed P0674 and P2291 side by side, forcing the technician to decide whether they were chasing an electrical fault or a fuel pressure problem. The only note on the job sheet was a single word: "Svårstartad" (hard to start).
When multiple systems flag errors simultaneously, finding the dominant failure is the priority. The diagnostic platform we build treats these two codes as independent failures. P0674 creates a cold start penalty, but P2291 is the primary reason the van will not fire up.
Testing the High-Pressure Fuel System
The engine control unit on a PSA DV6FD 1.6 BlueHDi requires a minimum fuel rail pressure of approximately 200 to 250 bar during cranking to release the injection signal. If the system cannot reach this threshold, the injectors remain shut.
Our engine ranked excessive internal return leakage (leak-off) in the fuel injectors as the most likely cause, at an 85 percent probability with high severity. If fuel pressure bleeds straight back to the return line, the required ignition pressure never builds during cranking. The suggested approach here is a leak-off test while operating the starter motor, alongside checking rail pressure buildup via live data.
Alternatively, a defective or sticking fuel pressure control valve carries a 65 percent probability of being the culprit. Whether the valve needle binds mechanically, the coil has abnormal resistance, or the O-rings are damaged, fuel slips past to the return. The resulting lack of rail pressure sets P2291. Verifying this requires a resistance and oscilloscope check of the PWM signal, plus a visual inspection of the valve's micro-filter and O-rings for damage or metal shavings.
Tracking Air in the Low-Pressure Circuit
If the high-pressure side checks out, the low-pressure circuit is the next suspect. The DV6FD uses a manual primer bulb and draws fuel from the tank through the filter. A clogged filter or a micro-leak at a quick connector, filter housing crack, or drain screw allows air into the system or lets fuel drain back to the tank while parked.
High-pressure pumps cannot compress air bubbles. If air enters the system, rail pressure either fails to build or rises too slowly during cranking. Our system ranked this at a 55 percent probability. Technicians should perform a visual check of the transparent hoses for air bubbles while cranking, measure the resistance of the manual primer bulb, and inspect the fuel for contamination in the filter bowl.
Locating the Glow Plug Fault
Fault code P0674 indicates an electrical open circuit or incorrect resistance for the cylinder 4 glow plug. Under the French PSA standard, cylinder 1 is counted from the flywheel side. This puts cylinder 4 furthest away, near the timing belt.
A burned heating element creates infinite resistance (an open circuit), which prevents preheating in that cylinder and makes cold starts difficult. However, it is entirely independent of the fuel pressure issues. Our system ranked this at an 80 percent probability for the P0674 code. Confirming it requires a resistance measurement of the glow plug against the engine block using a multimeter, followed by a voltage check at the plug connector with the ignition on.
Next Steps for the Workshop
Handling multiple unrelated codes requires isolating the mechanical facts from the electrical ones before tearing into the engine bay. I am curious how you approach split diagnostics like this in your own bays, do you tackle the fuel delivery first or clear the electrical codes before proceeding?