BRAND NEW *OEM Quality* Coolant Temperature Sender to suit Subaru Impreza GC GF GD GG, Liberty BF BC BG BD BH, Outback BG BH, Forester SF SG and SVX - 1989 to 2008.

Temperature gauge unreliable on your Subaru? The coolant temperature sender is the most common cause of erratic or stuck gauge readings across all EJ-series Subaru engines. This is a direct-fit OEM-specification replacement. Also suits the Subaru Impreza WRX and WRX STI. Same-day dispatch from Melbourne.

TO SUIT

This sender suits the full Subaru EJ-series engine family including Impreza GC GF GD GG (all variants including WRX and WRX STI EVO I-VIII), Liberty / Outback BC BF BG BD BH, and Forester SF SG with engines EJ16 EJ18 EJ20 EJ201 EJ205 EJ207 EJ208 EJ22 EJ25 EJ251 EJ255 EG33 from 1989 to 2008. Connector: 1-pin push-on blade. Thread: 1/8 GAS.

FITMENT CHECK

This is the temperature gauge sender only - it does not replace the ECU coolant temperature sensor. Both components look similar but serve different functions. If your check engine light is on for a coolant temperature fault you need the ECU sensor, not this sender.

OEM PART NUMBERS

21203-AA030
21203AA030

OTHER PART NUMBERS

TTS004

PACKAGE INCLUDES

1 x Coolant Temperature Sender (1-pin push-on blade terminal / 1/8 GAS thread)

ABOUT THIS SENDER

The coolant temperature sender is a single-wire thermistor that drives the temperature gauge. On Subaru EJ-series engines it is located on the engine block and is a known wear item - particularly on high-mileage WRX and STI engines that run hot under boost. It does not trigger fault codes when it fails.

An erratic or pegged temperature gauge on a boosted Subaru should not be ignored - if the sender is failing you lose the ability to monitor genuine coolant temperature. Replacing it is a low-cost first step before investigating the cooling system further.

COMMON SYMPTOMS OF FAILURE

Temperature gauge stuck at maximum or minimum
Gauge reading erratically or fluctuating
Gauge reads cold at operating temperature
Gauge reads hot immediately on cold start
Intermittent gauge behaviour

[04/93 - 10/00] SUBARU IMPREZA GC3 GC5 GC6 GC7 GC8 1.6L EJ16 / 1.8L EJ18 / 2.0L EJ20E EJ201 EJ205 EJ20G
[11/92 - 10/00] SUBARU IMPREZA GC8 WRX / WRX STI 2.0L EJ205 EJ20G (Turbo)
[02/99 - 10/00] SUBARU IMPREZA GC8 WRX STI 2.0L EJ205P 206kW
[04/93 - 10/00] SUBARU IMPREZA GF3 GF4 GF5 GF6 GF8 1.6L EJ16 / 1.8L EJ18 / 2.0L EJ20 EJ201 EJ205
[02/94 - 09/98] SUBARU IMPREZA GF8 WRX 2.0L EJ20G EJ205 (Turbo)
[09/99 - 12/07] SUBARU IMPREZA GD9 2.0L EJ201
[10/00 - 12/06] SUBARU IMPREZA GGA WRX / WRX Turbo 2.0L EJ205 EJ205 160-169kW
[11/01 - 09/05] SUBARU IMPREZA GDB WRX STi 2.0L EJ207 195kW
[01/01 - 09/05] SUBARU IMPREZA GDE 2.5L EJ251
[12/00 - 06/07] SUBARU IMPREZA GG9 2.0L EJ201
[01/89 - 07/94] SUBARU LIBERTY BC5 BC7 BF5 BF7 I 2.0L EJ20-GN / 2.2L EJ22
[06/94 - 11/98] SUBARU LIBERTY BD6 BD7 BD9 BG6 BG7 BG9 II 2.2L EJ22 / 2.5L EJ25D
[10/98 - 08/03] SUBARU LIBERTY BH5 BH9 III 2.0L EJ201 / 2.5L EJ25
[06/02 - 08/03] SUBARU LIBERTY BE5 III 2.0L EJ208 206kW
[01/96 - 12/99] SUBARU OUTBACK BG9 2.5L EJ25D
[01/00 - 08/03] SUBARU OUTBACK BH9 2.5L EJ25
[08/97 - 12/00] SUBARU FORESTER SF5 2.0L EJ202 / EJ205 Turbo
[02/02 - 12/08] SUBARU FORESTER SG5 S Turbo 2.0L EJ205
[06/02 - 05/08] SUBARU FORESTER SG9 2.5L EJ251 / EJ255
[09/92 - 12/97] SUBARU SVX CXW 3.3L Flat6 EG33

How do I test a coolant temperature sensor?

The most common test is to measure the sensor resistance with a multimeter at a known coolant temperature and compare against the manufacturer resistance curve. A cold engine (20 degrees C) typically reads 2,000 to 3,000 ohms and drops to around 200 to 300 ohms at operating temperature (90 degrees C). An OBD2 scanner showing a fixed temperature reading that does not change as the engine warms up is also a strong indicator of sensor failure.

Can a faulty coolant temperature sensor cause my engine to overheat?

Indirectly yes. If the sensor reports a lower temperature than actual, the ECU may not activate the cooling fan at the correct time, allowing the engine to overheat. It can also suppress the dashboard warning light, meaning you may not be alerted until the engine is already at a dangerously high temperature. Replace a suspected faulty sensor promptly.

Do I need to drain the coolant to replace the sensor?

Not always - many coolant temperature sensors can be replaced quickly with minimal coolant loss if you work fast and have a replacement ready to thread in immediately. However on some vehicles the sensor location requires partial coolant drainage. Check the sensor position on your specific engine before starting. Always use fresh coolant when topping up after replacement.

What are the symptoms of a faulty coolant temperature sensor?

Symptoms include poor fuel economy, black smoke, engine overheating warning, incorrect temperature gauge reading, hard starting when cold, and rough idle. Fault codes P0115 to P0119 are commonly associated with coolant temperature sensor faults.

Is it safe to drive with a bad coolant temperature sensor?

A faulty coolant temperature sensor can cause the ECU to run rich fuel mixtures and prevent the cooling fan from operating correctly, risking engine overheating. Replace it promptly - it is a low-cost part that can prevent expensive engine damage.

How do I know if my coolant temperature sensor or my thermostat is faulty?

A faulty thermostat typically causes the engine to overheat or never reach operating temperature. A faulty coolant temp sensor causes incorrect gauge readings and running issues but the coolant itself may be at the correct temperature. An OBD2 scanner showing live coolant temp data helps distinguish between the two.

Are there two coolant temperature sensors on my vehicle?

Many vehicles have two sensors - one for the ECU (engine management) and one for the dashboard temperature gauge. They look similar but are not interchangeable. Check your vehicle's service manual or contact us with your vehicle details to confirm which sensor you need.

Identification
SKU	CTS110-TTS004-8
Brand	Aftermarket OEM Replacement
Part Numbers
Part Number	TTS004
Reference OEM Number	21203AA030
Other OEM Numbers	21203-AA030, 21203AA030
Related Part Numbers	8342087703, 9465032520, CTS110, TS198, TTS004
Product Specifics
Product Type	SENSOR
Sensor Type	COOLANT TEMPERATURE GAUGE SENDER
Type	Sensor
Features	Direct Fit
Manufacturer Warranty	1 Year
Thread Size	1/8 GAS
Spanner Size	12mm
Number of pins	1 -pin connector
Connector Shape	Round
Fitting Depth	20 mm
Housing Colour	Black
Plug Type	Blade Terminal
Other Details
Note	Always verify fitment using your vehicle's OEM part number.
Unit Of Measure	ea