MIL light clears on engine re-start ; no fault codes stored

nsi-ltd

Zafira-B, 55 plate.

Engine hesitates and the MIL light comes on. Plugged in OBD reader and no fault codes are registered. MIL light clears on engine re-start without being reset by OBD.

Have monitored fuel rail pressure when fault occurs. Nothing irregular. Had fuel pump and regulator replaced by V* when 8 days out of warranty 🙁 Doesn't seem to be the culprit here.

Have replaced coil pack with genuine part, no change in symptoms.

Any ideas? Car is a good drive, but this condition is causing me to loose confidence and trust in this car.

vocky

possibly stretched timing chains or a duff lambda sensor

nsi-ltd

vocky said:
possibly stretched timing chains or a duff lambda sensor

Thanks Vocky, I hope it is not timing chain. I replaced both chains about 5k ago. I suppose I could monitor the lambda sensor voltage, but would have expected a stored code ???

vocky

chains should be okay if only done 5k, could also be a dodgy connection on the intake air temp sensor / MAF

nsi-ltd

Could be a possibility. All the sensors were stripped when I replaced the chains. Car is parked in my garage at the moment, but I will check all cables and connections when I next take it out.

Thanks.

nsi-ltd

Problem found and resolved 🙂

Fault code 1191-52 only came out when using OP-COM. My OBD-Key dongle and phone app (Auto Doctor PRO) did not show this code 🙁

Faulty Fuel Pressure sensor or wiring : Replaced sensor and the engine is now sweeter than ever.

Still miffed about the code resetting on engine start, and not being revealed by my OBD!