Engine Codes Explained
DISCLAIMER: The information in these documents are a collection from experience (friends or myself), magazine articles, mailing lists and Internet web sites etc. So don't take these as 100% correct gospel, hence I don't take any responsibility for any of these guides.
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Created: 10 Nov 2001
Updated: 24 April 2002
Revision 2

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C20XE, a 2L 16v fuel injection engine.

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E16SE, a 1.6L 8v fuel injection engine.

What are 'engine codes'?

Every engine in the GM range (i.e. includes Vauxhall, Opel etc.) has a engine code which represents the type of engine, its fueling type and its cubic capacity (cc in litres).

So what is the code system?

Each engine code usually begins with a letter, followed by 2 numbers and then either 2 or 3 letters after that. Lets take the following example:-


This is the engine code for the 2L 16v, DOHC, fuel injection engine as found in the Calibra, Astra and Cavalier cars. Lets split the engine code up. The letter 'C' is the type of exhaust or emission level standard. In this case C = EEC R 83.

The next 2 numbers is the engine cc, which is 2000cc (i.e. 2L). The next letter (X) is the engine compression ratio, in this case X = 10.0 to 11.5. The letter E is the fueling system, which E = multi-point fuel injection (petrol).

Where do I find the engine code?

The engine code shall be stamped below the cylinder head (up to 1993), usually on a small flat surface. But after 1993 the location moved to the edge of the cylinder block, transmission side.

  Engine Code System: To the top

The engine code system takes the following standard (Petrol engines):-


ie C20LET is a 2L Turbo injection engine with a CAT and a compression ratio of 8.5 to 9.0.

The engine code system takes the following standard (Diesel engines):-


ie 23DTR is a 2.3L Turbo diesel engine with increased output.

Code A
Exhaust Emission Unit
Code B
Engine Size (cc)
C EC 91/441/EEC, US ' 83 Two digit number represents the litre of the engine size, i.e. 20 is 2.0L and 35 is 3.5L. So engine size in litres x 10.
X EC 91/441/EEC, stage 2#
none ECE R 83 A (as R 15.04)
* ECE R 83 A (as R 15.04)
Note: * = any character, # = Stricter limits for ca.1996
Code C
Compression Ratio
Code D
Mixture system
G <= 8.5 E Multi-point Fuel Injection
L > 8.5 to 9.0 Z Central Injection
N > 9.0 to 9.5 D Diesel
S > 9.5 to 10.0 V Carburettor
X > 10.0 to 11.5    
Y > 11.5    

Code E
Specific Version (if quoted)
Code X Fuel system
C Corp. Ignition System
F Vehicles for Authorities
H High output/Supercharging
I Irmscher
J Throttled Output      
K Komplex      
L Low output/supercharging      
P Power adapted
R Increased Output
T Turbo
U Uruguay
V Volume model
W Venezuela
2 Family II engine

Special thanks go to http://perso.club-internet.fr and list members on the 'vauxhall_senator' mailing list for the help and advice on the construction of this engine code chart.

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