FAQ
TL;DR: DF192/DF208 that won’t clear usually trace to wiring or power: the rail sensor needs a 5 V feed, and “There sits EDC15. There are no miracles.” Check the sensor plug order and ECU supplies before replacing parts. [Elektroda, genek1000, post #16868789]
Why it matters: This FAQ helps Renault Trafic 1.9 DCI owners fix hard-start/no-start issues without wasting money on unneeded parts.
Quick Facts
- DTCs seen: DF192 (fuel rail pressure sensor) and DF208 (pressure control solenoid) reported as permanent. [Elektroda, Dzejuch, post #16867828]
- Observed rail pressure during cranking: 0 bar when the fault is present. [Elektroda, Dzejuch, post #16868408]
- Rail pressure sensor supply: 5 V from ECU; regulator supply: 12 V from a relay. [Elektroda, genek1000, post #16868789]
- Proven fix case: miswired 3‑pin rail pressure sensor plug; correcting wire order restored fuel delivery. [Elektroda, dawido250978, post #21638875]
- Replacing injectors, pump, and solenoid alone did not resolve DF192/DF208 in the cited case. [Elektroda, Dzejuch, post #16867828]
What do DF192 and DF208 mean on a Trafic 1.9 DCI?
DF192 flags the fuel rail pressure sensor circuit. DF208 flags the pressure control solenoid circuit. When both store as permanent, look for power, ground, or harness faults rather than failed hardware. The thread’s case showed both codes stuck even with multiple swapped parts. [Elektroda, Dzejuch, post #16867828]
Why do I see 0 bar rail pressure while cranking?
With DF192/DF208 active, the ECU may not read the sensor or control the regulator, so rail pressure stays at 0 bar. That matched the thread’s live data during start attempts. 0 bar plus permanent codes suggests an electrical issue, not a mechanical one. [Elektroda, Dzejuch, post #16868408]
Can a miswired rail pressure sensor plug cause a no‑start?
Yes. One documented fix was a 3‑pin sensor connector re-terminated with wires in the wrong order. The engine would not build pressure or start until the wire order was corrected. If your plug was replaced, confirm pin mapping matches the sensor. [Elektroda, dawido250978, post #21638875]
What voltages should I measure at the rail sensor and the regulator?
Measure a stable 5 V reference and ground at the rail pressure sensor, and 12 V supply at the pressure control regulator from its relay. Loss of either supply sets DF192/DF208 and blocks pressure rise. "The pressure sensor has a 5 Volt power supply... regulator has a 12v supply." [Elektroda, genek1000, post #16868789]
How do I quickly check the low‑pressure side before chasing wiring?
Disconnect the outlet at the filter and prime with the hand bulb ("pear"). Fuel should flow freely. In the thread, this check confirmed supply to the pump, focusing diagnosis on the rail sensor/regulator circuits. This saves time before deeper electrical tests. [Elektroda, pp_pablo, post #16868448]
Will starting fluid (ether) help me narrow the fault?
If the engine runs briefly on ether, air and compression are likely fine, and the problem lies with fueling or its control. The case vehicle ran only on ether, correlating with 0 bar reported rail pressure and permanent DF192/DF208. [Elektroda, Dzejuch, post #16868213]
How do I troubleshoot DF192/DF208 in three steps?
- Key ON: verify 5 V reference and ground at the rail sensor; check for 12 V at the regulator.
- Wiggle-test the harness while monitoring voltages; repair any dropouts.
- If voltages are good, scope or swap-test the circuits at the ECU connectors to isolate wiring breaks.
Each step targets the ECU supplies these circuits require. [Elektroda, genek1000, post #16868789]
Could a camshaft position sensor cause these specific codes?
The OP considered the cam sensor, but the unmoving 0 bar rail pressure and permanent DF192/DF208 point first to the fuel-pressure sensor/regulator circuits or their supplies. Fix those before chasing timing sensors. Electrical faults here prevent any pressure rise. [Elektroda, Dzejuch, post #16868408]
What is EDC15 on the Trafic?
EDC15 is the Bosch diesel engine control unit used here. It supplies 5 V to the rail sensor and controls the pressure regulator via a 12 V-fed circuit. As one expert put it, “There sits EDC15. There are no miracles.” Validate its inputs and outputs. [Elektroda, genek1000, post #16868789]
I replaced injectors, the pump, and the solenoid. Why won’t it start?
Parts replacement did not help in the cited case because the root cause was electrical. The ECU still logged DF192/DF208 as permanent and rail pressure stayed at 0 bar. Test wiring, grounds, and connector pin order before more parts. [Elektroda, Dzejuch, post #16867828]
Do permanent (not erasable) DF192/DF208 mean a hardware failure?
Permanent, non-clearable DF192/DF208 usually indicate a present circuit fault: open/short wiring, missing 5 V/12 V, or wrong pin order. In the thread, faults were present even before cranking, pointing away from mechanical causes. [Elektroda, Dzejuch, post #16868408]
I even tried another ECU; what does an unchanged fault imply?
If swapping the ECU leaves DF192/DF208 unchanged, focus on vehicle-side wiring, connectors, power, grounds, and sensor plug integrity. The case saw the same behavior with a different computer, strengthening the harness/plug suspicion. [Elektroda, Dzejuch, post #16871632]
