About this pump
The 03C121004J water pump is the INA-built coolant pump for the 1.4 TSI and 1.4 TFSI EA111 engine family, the engine that carried Golf 5 and Golf 6, Jetta, Tiguan, Touran, Scirocco, the Audi A1 8X and A3 8P, Octavia II and the SEAT Leon and Ibiza of the same years. It is supplied with the glued-in sealing ring that arrived with the J revision, and it is a genuine OEM part, brand new, INA brand number 538 0732 100.
water pump — Genuine OEM coolant pump built by INA (INA number 538 0732 100) for the 1.4 TSI / TFSI EA111 engine family, supplied with the bonded sealing ring that arrived with the J revision.
OE/OEM Part Number:
03C121004J, 03C121004B, 03C121004C, 03C121004D, 03C121004E, 03C121004G, 03C121004H, 03C121004K, 03C121004L, 03C121004JV, 03C121004JX
INA: 538 0732 100
Pierburg: 7.10942.10.0
That engine family is one of the most common four-cylinder units in Europe, and its cooling system is also one of the most frequently misdiagnosed. This listing is written so you can work out whether the pump is actually your fault before you spend money on it.
What the J revision actually changes
The sealing ring is glued in. On 03C121004B through 03C121004L the pump carried a separate rubber O-ring sitting in a groove on the housing. The J revision bonds the ring to the aluminium housing instead. That has two practical consequences: there is no loose ring to swap, and you must not add sealant or a second gasket on top of the bonded ring. It seals on contact pressure against a clean, dry, machined face. Sealant under a bonded ring is the most common reason a fresh pump weeps again within a few thousand kilometres.
It supersedes the early family. 03C121004J replaces 03C121004B, C, D, E, G, H, K and L, plus the JV and JX supplier codes. Casting, bolt pattern, impeller and outlet spigot are unchanged; only the sealing method moved forward, which is why the later number drops straight onto an early car.
It is a pump, not a thermostat module. On the EA111 1.4 TSI the coolant pump and the thermostat are separate castings on the same side of the block. This part is the pump only. If the engine runs cold, warms slowly or throws a map-controlled cooling fault, you are looking at the thermostat housing, not here.
How these pumps fail, and what you will notice first
1. The shaft seal starts to weep. Coolant escapes past the mechanical seal and runs down the back of the pump. Because the block is hot, most of it evaporates before it reaches the floor, so the first symptom is usually a slow, unexplained drop in the expansion tank rather than a puddle. Look for a chalky pink or white crust on the pump underside and on the block directly below it. A crust that is dry today still means the seal is on its way out.
2. The impeller lets go. The pressed impeller can slip on its shaft. The pump still turns quietly and shows no leak, but circulation collapses: the heater blows cold at idle and only warms up when you rev the engine, and the temperature gauge climbs in traffic then drops again once you are moving.
3. Bearing noise. A rumble or whine from the front of the engine that rises with engine speed, worst when cold. By the time you can hear it the seal is usually already weeping.
Confirm it before you buy. Pressure-test the system cold at 1.2 to 1.5 bar and watch the pump area for a slow bleed-down. Then run the engine to operating temperature with the heater on full heat and check that both heater hoses are equally hot. A pump that leaks but still circulates is a leak repair; a pump that circulates badly with no leak is usually an impeller. Both are this part.
Fitment
The table lists the models this pump is sold for. Engine code decides fitment, not model year — the same body was built with 1.4 MPI, 1.4 TSI and 1.6 MPI engines, and only the TSI / TFSI EA111 units use this pump. Check the engine code on the sticker in the spare-wheel well or on the timing cover before ordering.
| Make | Model | Years | Engine / Code |
|---|---|---|---|
| VW | Golf V / Golf VI, Golf Plus | 2005 – 2014 | 1.4 TSI: BLG, BMY, CAXA, CAVD, CNWA, CTKA |
| VW | Jetta III / IV, Eos | 2006 – 2016 | 1.4 TSI: CAXA, CAVA, CAVD, CMSB, CTHA, CTHD |
| VW | Passat B6 / B7, CC | 2008 – 2016 | 1.4 TSI: CAXA, CTHD |
| VW | Scirocco III, Beetle | 2009 – 2016 | 1.4 TSI: CAXA, CAVD, CNWA, CTHD, CTKA, CMSB |
| VW | Tiguan I, Touran I, Sharan II | 2007 – 2017 | 1.4 TSI: BWK, CAVA, CAVB, CAVC, CAVD, CTHA |
| Audi | A1 8X / S1, A3 8P | 2008 – 2014 | 1.4 TFSI: CAXA, CAXC, CNVA |
| Skoda | Octavia II, Superb II, Yeti, Fabia II | 2008 – 2016 | 1.4 TSI: CAXA, CAXC |
| SEAT | Ibiza IV, Leon 1P, Altea, Toledo, Alhambra | 2006 – 2015 | 1.4 TSI: CAVA, CAXC, CNWB, CTHA |
Before you order — four numbers that must not be mixed up
03C121004 vs 04E121600AA. The 04E number is the EA211 engine, the later family with the pump built into a thermostat module. It looks similar in photographs and does not fit an EA111 block.
03C121004J vs 036121005. The 036 number is the 1.6 16V and 1.6 FSI pump from the Golf IV era. Different casting, different bolt spacing.
Pump vs thermostat housing. If you also need the thermostat, that is a separate 03C121111-series part. Buying the pump alone will not cure a cold-running engine.
Do not reuse the old ring. The J revision’s ring is bonded to the housing. If your old pump used a loose O-ring, that ring stays with the old pump and goes in the bin.
Installation notes that save a second strip-down
Clean the mating face properly. Old bonded-ring residue and hardened coolant leave a film that looks flat but is not. Scrape with a plastic blade, then finish with a fine abrasive pad, and wipe the face dry with brake cleaner. No sealant, no grease, no gasket.
Torque evenly. Run the bolts down in a cross pattern in two stages. The housing is aluminium and distorts if you pull one bolt fully home first.
Fill under vacuum if you can. The EA111 cooling circuit traps air in the heater matrix and the head. Vacuum fill avoids the long bleed, but if you are filling by hand, open the bleed screw on the heater hose, fill slowly until a steady stream runs with no bubbles, then run the engine to full temperature with the heater on hot and top up once it cools. Use G12++ / G13 to the correct concentration — mixing silicate and OAT coolants gels the system.
Check the belt path while you are in there. On most applications the pump sits behind the front engine cover, so inspect the belt and tensioner before you close it up. Doing the pump twice because a tired tensioner was left in place is an expensive habit.
Shipping and packing
Orders leave within one to two working days of cleared payment. The pump is packed in a moulded insert with the outlet spigot protected, so the bonded ring arrives undistorted. Tracking is emailed when the parcel is handed to the carrier. Customs charges, where they apply, are the buyer’s responsibility.
Condition & warranty
Brand new, genuine OEM INA unit, twelve months warranty against manufacturing defects. The warranty covers the pump as supplied. It does not cover leaks caused by sealant applied to a bonded ring, by a scored or distorted mating face, by running the engine dry, by the wrong coolant, or by damage from an over-tightened or cross-threaded bolt. If a unit is faulty on arrival, send us photographs of the ring and the housing face before returning anything.
Not sure it is the pump?
Send us the engine code, the part number on the old pump and a photograph of the leak area. We will tell you whether the fault sits in the pump, the thermostat housing or the expansion cap — that answer is free and it stops you buying a part you do not need.
Wholesale
Tiered pricing for 1 pc, 5 pcs and 20 pcs is shown below. Workshops and resellers rebuilding EA111 cooling systems should ask for a combined quote — we price pumps, thermostat housings and timing components together, and we can hold stock for a repeat fleet customer.
