Peugeot 307 1.6 HDi 9HX: P0490 and P1162 EGR EDC16C32 Errors Persisting After Fixes

motorriderrm wrote:

@ElektrodaBot provide solution to problem

Direct response (summary of solution from thread)
- Confirmed solution (author's post of 11 May 2021): the faults were two at the same time.
1) The EGR valve had an internal "sticking" to ground (short circuit in the position sensor track).
2) An additional fault in the wiring harness (break/short circuit).
- Repair: replacement of the faulty EGR with a functioning one + repair/rebuild of parts of the harness; after that adaptation of the EGR with the "parts replacement" function in Diagbox/Planet.
- This explains: immediate return of P0490/P1162 already on the ignition itself, no EGR position signal in "live data" and inflated MAF (common 5 V line).

Detailed analysis and verification and repair procedure
1) Symptoms and their significance
- P0490 and P1162 (copying EGR position) return as soon as cleared, still without starting: The ECU sees the signal from the EGR position sensor out of range (usually 0 V when shorted to ground or "too high" when shorted to plus).
- No EGR position in the actual parameters: the signal path is pulled down/cut off.
- Exaggerated MAF at idle (+~200 units): typical effect of a loaded or undervolted 5 V line, which in 1.6 HDi is sometimes shared by EGR (position sensor), MAF and fuel pressure sensor.

2) Why is the 12 V "not there" on the coil pin "dry"
- The 12 V supply/engine control of the EGR/throttle usually only appears when the (PWM) is driven. The absence of constant 12 volts when the plug is unplugged is not yet evidence of a fault.

3) Pinout (typical for DV6, check by VIN/scheme of the specific ECU)
- Pin 1: 5 V ref (EGR position sensor).
- Pin 3: drive power/control (12 volts when driven).
- Pin 5: signal ground.
Note: details may vary depending on EDC version (EDC16/EDC17) - always verify at ServiceBox/Diagbox by VIN.

4) Tests that showed the fault (and how to perform them correctly)
- The '100 W bulb' test only confirmed continuity of the thick wires, but did not detect inter-wire leakage/shorts on the 5 V and signal lines. In sensor systems, this is not enough.
- Recommended procedure:
- Disconnect the EGR and ECU plug (both sides unzipped).
- Check each wire of the harness:
- Continuity (Ω ≈ 0...0.5 Ω on short lengths).
- Insulation to earth and between conductors (resistance should be >1 MΩ; any value on the order of kΩ or lower indicates leakage/short circuit).
- Measure the 5 V line on the ignition with the sensors connected, then unplug in sequence: EGR → MAF → fuel pressure sensor. If after unplugging any component the 5 V returns from e.g. 2.5-4.0 V to ~5.0 V - you have the culprit (component or its harness).
- Check the EGR valve itself on the table: by applying 5 V to the sensor track and mechanically moving the plug, the signal voltage should change smoothly (approx. 0.5-4.5 V). Signal "stuck" to 0 V or rapid spikes = damage to the EGR sensor/electronics (here: internal short circuit to ground).
- "Wiggle test" the harness at typical DV6 chafing points (around the air filter housing, under the battery/battery pack, at the EGR/throttle mounts, at the transitions through the mounts and edges). Very often this is where leakage/periodic breaks come out.

5) Final repair and verification
- Replace the EGR with a branded (e.g. Valeo/Pierburg) or documented working one. In the case described, a "new" replacement did not rule out the problem because there was a coexisting harness fault and/or the EGR itself was faulty.
- Repair the harness: cut out the damaged sections, insert a new wire of the same diameter and insulation, solder with Sn60Pb tin or crimp connectors + heat shrink with glue, reconstruct the pessels and fixing points, reposition the route so that it does not rub against sharp edges/grips.
- Adaptation in Diagbox/Planet: function "replacement of parts → EGR valve" (trim ends, initialisation). Universal HDi testers often "lie down" on this function.
- Check after test drive:
- No DTC return after 2-3 ignition/drive cycles.
- 5 V ref stable 4.95-5.05 V.
- In "live data": "EGR position commanded" ≈ "EGR position actual" (slight difference, no "sticking" at 0%/100%).
- MAF at idle returns to nominal values (no permanent overboost).

6) Why it was "masking" each other
- An internal EGR short to ground was pulling down the signal line (and could load the 5 V reference), so the ECU immediately reported P0490/P1162 on the ignition itself. At the same time, damage to the harness was causing a discontinuity or leakage, so replacing the EGR did not give any improvement. This is a classic case of two superimposed faults.

Practical and safety tips
- Do not use a 12 volt bulb/probe to test the 5 volt and signal tracks - risk of damaging the ECU. Use high impedance multimeters and controlled loads for these lines (e.g. 1-2 kΩ resistor for 5 V load test).
- If the 5 V "sits down" to ~2.5 V - it is almost always the component/binding on the same reference that is to blame. Unplugging one at a time usually quickly reveals the culprit.
- Always disconnect the battery before working on the harness; check voltage drops and insulation resistance after soldering.

What to do next (if you are diagnosing a similar case)
- Provide VIN, ECU type (EDC16C34/EDC17), year, and "live data" dump (EGR set/current position, 5 V ref, MAF at idle, EGR signal voltage).
- I can break down by pin the typical EGR/MAF/5 V path connections for your version based on the schematic (wire colours, ECU connector numbers and intermediate connector locations) so you can check the specifics without wandering off.

Summary: In the topic described (ID 3314467), the final repair was to fix two faults at the same time - replacing the EGR with a short to ground and repairing the faulty harness - followed by an EGR adaptation in Diagbox/Planet. After these measures the parameters returned to normal and the errors did not return.