P0117 on Volkswagen
Engine Coolant Temperature Sensor Circuit Low
P0117 on Volkswagen vehicles indicates engine coolant temperature sensor circuit low. Au7o has documented this code across 5 Volkswagen models — most commonly on Golf, Golf R, GTI. This code means the engine coolant temperature (ECT) sensor is reading too low a voltage, which the computer interprets as an impossibly high coolant temperature. In most cases this is an electrical fault — such as a short to ground in the wiring — rather than the engine actually overheating. The coolant temperature signal affects fuel mixture, cooling fans, and other functions, so a bad reading can cause poor running, hard starting, or fans running constantly. The fault is usually in the sensor or its wiring. Typical repair costs on Volkswagen range from $30 to $350, depending on the specific model and root cause.
Common Causes of P0117
- •Faulty engine coolant temperature sensor
- •Short to ground in the sensor signal wire
- •Damaged or corroded wiring/connector at the sensor
- •Coolant contamination affecting the sensor
- •Poor electrical ground
- •Faulty PCM/ECM (less common)
P0117 on Volkswagen by Model
Volkswagen Golf(1 issue)
- Plastic coolant flange / 'blue' temperature sensor leaking at rear of head1993-1999
The coolant outlet flange (a molded plastic housing at the rear/transmission end of the cylinder head) and the two-pin coolant temperature sensor mounted in it are a classic, high-frequency VW failure. The plastic flange warps and cracks under constant heat and pressure, and the sensor's plastic body and O-ring degrade, both causing a slow coolant leak from the back of the engine, often hard to see. On the VR6 the flange is buried and awkward to reach. Loss of coolant leads to overheating; a failing blue temp sensor also causes poor cold-start running and erratic gauge/fan behavior.
Volkswagen Golf R(1 issue)
- Engine Coolant Temperature Sensor / Inaccurate Temp Gauge2015-2021
Separate from the well-known water-pump/thermostat-housing leak, MK7-platform Golf R owners report failures of the engine coolant temperature (ECT) sensor and a notably unreliable dashboard temperature gauge. The gauge tends to sit pinned at ~90C and gives little warning before overheating, so coolant loss or a failing sensor can let the engine run dangerously hot without alerting the driver. A faulty ECT sensor also causes erratic readings, false overheat warnings, poor cold-start fueling/economy, and a check engine light. VW updated early sensor revisions.
Volkswagen GTI(1 issue)
- Plastic coolant flange and blue temperature sensor failure1993-1999
MK3 Golf/GTI models use a plastic coolant flange/housing on the cylinder head that warps and cracks from repeated heat cycling, and the 'blue' coolant temperature sensor that lives in it also fails intermittently. The flange leaks coolant, while a failing sensor feeds bad data to the ECU (rich/lean running, fluctuating gauge, hard cold starts, coolant warning light). Affects both the 2.0 8v and VR6. Note the black sensor drives the cluster gauge and the blue sensor feeds the ECU.
Volkswagen Jetta(1 issue)
- Coolant Temperature Sensor (Blue/Black Top) Failure1993-1999
Early MK3 Jettas were fitted with an engine coolant temperature (ECT) sensor with a black or blue top that is prone to internal failure. When it sends bad data, the ECU miscalculates fuel and timing, and the dash temperature gauge reads erratically or the cooling fans fail to switch on/off correctly. Volkswagen released an updated, more-reliable green-top sensor (part 059 919 501A), which became the de facto fix carried across MK3/MK4. It was never a formal recall but is one of the most widely recognized VW fixes of the era. Any MK3 still wearing the original blue/black sensor is a strong preventative-replacement candidate.
Volkswagen New Beetle(1 issue)
- Engine Coolant Temperature Sensor (G62) Failure1998-2006
The early black-topped coolant temperature sensor (G62, often on the coolant flange below the upper radiator hose) is a well-known weak point on the 2.0 8V and 1.8T New Beetle. The plastic sensor and its flange crack or the sensor sends erratic readings, causing the temperature gauge to swing or read falsely hot/cold, hard cold starts and rich/lean running, and a check-engine light. The original black sensor was superseded by an updated green sensor. Because the ECU uses this signal for fueling and fan control, a failed sensor can mimic a thermostat or head-gasket problem and trigger unnecessary repairs.
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View P0117 across all makes →Frequently Asked Questions
What does P0117 mean on Volkswagen?▼
P0117 stands for "Engine Coolant Temperature Sensor Circuit Low." This code means the engine coolant temperature (ECT) sensor is reading too low a voltage, which the computer interprets as an impossibly high coolant temperature. In most cases this is an electrical fault — such as a short to ground in the wiring — rather than the engine actually overheating. The coolant temperature signal affects fuel mixture, cooling fans, and other functions, so a bad reading can cause poor running, hard starting, or fans running constantly. The fault is usually in the sensor or its wiring. On Volkswagen specifically, this code is documented across 5 models.
What causes P0117 on Volkswagen vehicles?▼
Common causes on Volkswagen: Faulty engine coolant temperature sensor, Short to ground in the sensor signal wire, Damaged or corroded wiring/connector at the sensor, Coolant contamination affecting the sensor, Poor electrical ground. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0117 on a Volkswagen?▼
Repair costs on Volkswagen range from $30 to $350, depending on the specific model and root cause.
Which Volkswagen models have P0117 documented?▼
Au7o has documented P0117 on 5 Volkswagen models: Golf, Golf R, GTI, Jetta, New Beetle.