Can not working upstream sensor cause engine overheat?

Question

I was in service and they removed the FAP filter and programmed the engine computer so that it would not ask it.

But there were still errors and they said I need to change the upstream sensor. I asked what bad can happen if I drive with not working sensor. They said the engine can overheat.

When I went to another service to replace the sensor, they said this is nonsense. They said that first service done programming work badly. And so they reprogrammed, and said this sensor is not needed.

I also googled and did not find info about overheating engine. I found something about exhaust system, which might make sense.

So did the first service lied/or do not know what they are talking about?

My car is peugeot 406, 2.2 HDI

Answer 1

I've never heard of a bad O2 sensor - upstream or downstream - causing overheating. If the computer can't read the sensor, it will tend to run rich - i.e., more fuel - which will actually produce cooler the exhaust and, by extension, remove a little more heat from the system.

Unless there is something really odd about your Peugeot, the first shop was incorrect.

A bad O2 sensor will, however, reduce fuel economy. If left uncorrected for a long time, it also can damage your catalytic converter(s).

Answer 2

Yes, no, I don't know. The heated exhaust gas oxygen (HEGO) sensor is used to establish fuel air ratios on some vehicles. You could run rich or lean. I've personally seen a vehicle with long term HEGO fault that caused continued preignition to to point that the bottom of the pistons broke off past the rings. Vehicle overheat... no. The pistons broke. Hint: that's a mighty expensive repair.

Recommendation. Get vehicle to design intent. Repair or replace all inoperable sensors. They are pretty cheap to replace. If you are in the USA Autozone has an awesome tool in the free tool loaner program that makes this a ten minute repair for the Do It Yourself person. The biggest problem is the repair is best done on a hot exhaust. You need to be careful to not burn yourself.

I will say, I'm a bit confused by your posting. What, pray tell is a FAP filter? I have no clue what that is. Best practice is to define mystery abbreviations When First Used (WFU).

You also mentioned the dealer "programming" the engine computer. That sounds pretty odd to me. In my experience (not with Peugeot, but with a United States based Manufacturer) engine computer reprogramming is a mighty rare event. It does happen, but not very often.

Its more likely that the dealer reads stored fault codes (OnBoard Diagnostic (OBD2) codes, and erased them. Is that a possible interpretation?

I wouldn't necessarily call either service team dishonest... Best action for the long term reliability of your car is to fix defects to manufacturer's design intent.