16500 on 1996-2001 Audi A4 — Engine Coolant Temp. Sensor (G62): Implausible Signal
1 vehicles · 1 makes · $30-$180 repair
How to diagnose and fix 16500: most-reported vehicles
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Audi A4 · 1996–2001
The original black-housing dual coolant temperature sensor (G62) mounted in the coolant flange at the back of the cylinder head develops cracks and fails internally. The temperature sensor G2 (also known as G62) for the gauge has likely failed and is relatively easy to fix; it is located in the coolant flange at the back of the cylinder head and the early square-connector style and later elongated D-shaped black connector sensors are known problematic units. When it fails the ECU sees an implausible coolant temperature, leading to cold starting difficulties at low temperatures, poor idle and acceleration during warm up as well as an erratic or dead temperature gauge.
Common Symptoms
- erratic or dead coolant temperature gauge
- hard cold starts
- rough idle during warm-up
- poor fuel economy
- rich-running condition
- check engine light
How to Fix
Scan with VAG-COM/VCDS for fault 17664 / 16502 (P0118) and bench-test the sensor's resistance. From Bentley, the G62 test procedure: allow engine to cool to room temp (68F/20C), disconnect ECT sensor, connect multimeter to terminals 1 and 2; resistance must be 1500 to 3000 ohms — if not, replace the ECT. Replace with the updated green-top OEM sensor (part 059 919 501A) along with the retaining clip (032 121 142) and O-ring; replacing this sensor resolves running issues for many owners who are still using the original black sensor which had a high failure rate. Part is ~$25-40, DIY 30 minutes; shop labor brings total to ~$80-180.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Engine Coolant Temperature SensorCross-refTSE 1D
Fitment confirmed against the ShowMeTheParts catalog for this vehicle's year and engine.
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Sources for this issue (1)
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16500 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does 16500 mean?
16500 stands for "Engine Coolant Temp. Sensor (G62): Implausible Signal." This VAG (VW/Audi/SEAT/Skoda) fault code, equivalent to OBD-II P0116, indicates the engine control module has received an implausible or out-of-range signal from the engine coolant temperature sensor (G62). It means the coolant temperature reading does not correlate logically with expected values (for example, the sensor reports a sudden, unrealistic temperature drop or fails to track engine warm-up). This can cause incorrect fueling, high or fluctuating idle (often 1200-3000 rpm on a warm start), and erratic temperature gauge behavior.
What are the most common causes of 16500?
The most common causes of 16500 are: Faulty/aging engine coolant temperature sensor (G62) — the older black sensors on 1995-2002 VAG cars are a known weak point, superseded by green units, Corroded, loose, or damaged connector at the G62 sensor, Wiring faults (open, short, or chafing) in the coolant temperature sensor circuit, Poor ground or reference voltage to the sensor, Low coolant level or air pockets causing the sensor to read inconsistent temperatures, Faulty engine control module (rare). The specific cause varies by vehicle.
How much does it cost to fix 16500?
Repair costs for 16500 range from $30 to $180, depending on the vehicle and root cause.
Which vehicles are affected by 16500?
Au7o has documented 16500 across 1 vehicle models from 1 manufacturers: Audi.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.