Citroën C4 Turbo

Turbo Citroën C4: from the DV6ATED4 to the EB2ADT and 5GF, two decades of engine codes not to be confused

On the C4, the engine code is the only reliable reference for avoiding ordering errors. Engine capacity alone is not enough: the 1.6 HDi is available under the codes DV6ATED4 (90 and 92 hp), DV6TED4 and DV6C (110 and 112 hp), then 9HD, 9HY and 9HZ for the 110 hp versions of a later generation — three distinct turbo families, none of which are interchangeable. Checking the code stamped on the block before placing any order is essential.

Diesel: from the first C4 to the C4 Spacetourer, the 2.0 HDi and BlueHDi in focus

The 2.0 HDi covers several power outputs depending on the code: RHE and RHH appear in both the 150/160 hp HDi and BlueHDi versions as well as the 150/163 hp versions, whilst RHC is specific to the 150/163 hp versions and AHR to the HDi and BlueHDi 150/160 hp versions. The 1.8 HDi 150 hp carries the codes 4N13 and 6HZ, not found in any other engine capacity. More recently, the 1.5 BlueHDi 110 hp is identified by the codes 5WZ-HV, 5WZ-TV or YHS, and the 1.6 BlueHDi 100 hp by the single code BHY. On these diesel engines, variable-geometry turbos are prone to fouling caused by the EGR circuit and DPF: a whistling turbo, a gradual loss of power, or the vehicle entering limp mode are often early signs of a lubrication or deposit problem, well before any outright mechanical failure. The root cause must be identified and resolved before any replacement is carried out.

Petrol turbo: EP6DT, EP6FDT, EB2 and 5GF — four codes, four different turbos

On the petrol side, the C4 received several generations of turbocharged engines. The 1.6 THP 150 hp with engine code EP6DT and the 1.6 THP 150/156/165 hp with engine code EP6FDT do not share the same turbo despite having an identical engine capacity. The 1.6 PureTech 180 hp carries the code 5GF and uses a specific fixed-geometry turbo. The 1.2 three-cylinder engines are split into two groups: EB2DT and EB2DTS for the THP 110 and PureTech 130 hp, EB2ADT and EB2ADTS for the PureTech 110/130 hp and THP 110/130 hp. On the small three-cylinder engines, bearing fragility when oil has degraded or when the engine is started cold without allowing oil pressure to build is a well-documented weakness. The majority of turbos in this range are available as new units; the 1.6 HDi 110 hp (codes 9HD, 9HY, 9HZ) is also available as a reconditioned turbo, sold on an exchange basis.