Parts for your 2009 Audi Q5-Temperature sensors

2009 Audi Q5 temperature sensors — what they do and when to sort them

Based on Audi technical sources — including the Audi Q5 Self‑Study Program (SSP 397), Audi ElsaWin repair manuals for the 8R platform, and ETKA parts catalogues — the 2009 Audi Q5 absolutely uses multiple temperature sensors. These include the engine coolant temperature sensor (G62), intake air temperature sensor (often integrated with the MAF), ambient/outside air temperature sensor (G17), exhaust gas temperature sensors on many diesel and some petrol variants, plus HVAC and transmission-related sensors. So temperature sensors are very much relevant on this model.

On the Q5, temperature sensors feed live data to the engine control unit and climate systems so everything runs spot on. They help the ECU trim fuel on cold starts, trigger the radiator fans, manage turbo and ignition timing under load, and, on diesels, protect the DPF by monitoring exhaust heat. In day-to-day terms, that means better drivability, reliable heating and cooling, proper emissions control, and the best chance at long engine life.

There’s no set replacement interval in Audi’s servicing schedules for most sensors — they’re “replace on condition” items. But after well over a decade on the road, failures aren’t rare. Common signs include hard cold starts, a stuck high or low temperature reading on the dash, the A/C behaving oddly, the radiator fans running flat out, or the MIL lighting up with codes like P0116/P0118 (coolant temp), P0070 (ambient temp), P0544 (EGT), or IAT-related faults.

Good practice during servicing a 2009 Audi Q5:

• Scan the car and check live data. Compare coolant temp to a cold engine/ambient reading — they should align before start-up.
• Inspect connectors and wiring under the bonnet and front bumper for corrosion or damage, especially after minor knocks.
• For coolant temperature sensor replacement, only work on a cold engine, relieve system pressure, and refresh coolant with the correct spec. Bleed air properly.
• If the intake air temp is combined with the MAF, avoid over-oiling aftermarket filters and don’t touch the sensing element.
• Diesel Q5s rely on EGT sensors for DPF health. If there are regen issues, test the EGTs and replace any lazy or open-circuit units in pairs where appropriate.

When fitting replacements, stick with quality OEM-equivalent parts. A fresh sealing O-ring for the coolant sensor, correct routing of wiring looms, and a quick road test with live data will save headaches and keep the Q5 happy across Aussie and Kiwi climates.

Popular questions

Where is the engine coolant temperature sensor on a 2009 Audi Q5?
On most Q5 engines of this era, the coolant temperature sensor is fitted in a coolant flange or housing on the engine — commonly at the rear or side of the cylinder head. Access varies by engine variant (2.0 TFSI, 3.2 FSI, 2.0/3.0 TDI), so removing the engine cover and some intake ducting may help. Look for a small two‑pin connector and a plastic-bodied sensor with an O‑ring.

If you’re unsure, a quick check of the ElsaWin repair manual or a parts diagram for your exact engine code will pinpoint it, and you can confirm with a scan tool by watching live temp data while gently warming the engine.

Do temperature sensors need routine replacement on the Q5?
No set interval is listed, they’re replaced when faulty. That said, given the age of a 2009 Q5, a preventative coolant temp sensor swap can be sensible if there are any erratic readings, hard starts, or fan control oddities. Always diagnose first — a wiring fault or thermostat issue can mimic a bad sensor.

For intake and ambient sensors, cleaning connectors and ensuring proper mounting often restores accurate readings without parts replacement.

What happens if an exhaust gas temperature (EGT) sensor fails on a diesel Q5?
The ECU may limit power, increase fan operation, trigger the MIL, and suspend or botch DPF regenerations. Left unchecked, that can lead to soot loading and further faults. Scanning for P0544/P247A-type codes and checking live EGT values will confirm. Replace any failed EGTs promptly and force a proper DPF regen if required.