Jaguar Engine Code Decoder: List, Meaning & Numbering

A Jaguar engine code is stamped on the block and encoded in the VIN. The most common codes are AJ126 (3.0L V6 supercharged), AJ133 (5.0L V8 supercharged), 204DTD (2.0L Ingenium diesel), and 204PT (2.0L Ingenium petrol).

Code format: usually 3–6 alphanumeric characters, often with a suffix indicating power or market variant [THIRD-PARTY - Jaguar workshop manual]
VIN position 8: the engine code is embedded in the VIN – position 8 is the engine code letter for most modern Jaguars [THIRD-PARTY - OEM VIN decoding standard]
Block stamp: located on the lower front or rear of the block, visible from under the bonnet on most models
Last verified: March 2026 against Jaguar workshop data

Full decoder table, how to read the code, common mistakes, and related specifications below.

Full Jaguar Engine Code Decoder Table

This table lists every Jaguar engine code used in UK-market production since the 1990s. Codes are cross-referenced to the model, chassis, and displacement. Where multiple variants exist, the suffix is noted.

Engine Code	Displacement	Type	Models Fitted	Years	Notes
204DTD	2.0L	I4 Diesel	XE, XF, F‑PACE, E‑PACE	2015–2024	Ingenium diesel; AJ200D variant
204PT	2.0L	I4 Petrol	XE, XF, F‑PACE, E‑PACE	2017–2024	Ingenium petrol; AJ200P variant
AJ126	3.0L	V6 SC	XF, XJ, F‑TYPE, F‑PACE	2012–2020	3.0L supercharged V6
AJ133	5.0L	V8 SC	XJ, F‑TYPE, XK	2009–2024	5.0L supercharged V8; pre-2013 tensioner watch
AJ-V8	4.0L / 4.2L	V8 NA/SC	XJ, XK, S‑TYPE	1996–2009	Earlier naturally aspirated and supercharged V8s
276DT	2.7L	V6 Diesel	XF, XJ, S‑TYPE	2004–2012	Ford-Lion V6 diesel; oil pump weakness
306DT	3.0L	V6 Diesel	XF, XJ, F‑PACE	2009–2020	SDV6; crankshaft bearing fatigue
AJ20D6	3.0L	I6 Diesel	XF, F‑PACE	2020–present	Straight-six diesel, replaces 306DT in some models
AJ6 / AJ16	2.9L / 3.2L / 3.6L / 4.0L	I6 Petrol	XJ, XK	1984–1996	Classic straight-six family
XK6	2.4L / 2.8L / 3.4L / 3.8L / 4.2L	I6 Petrol	XJ Series 1–3, E‑Type	1948–1990	Legendary XK straight-six
V12	5.3L / 6.0L	V12 Petrol	XJ-S, XJ12, XJR‑15	1971–1996	Jaguar V12, 5.3L and 6.0L variants
Duratorq 2.0	2.0L	I4 Diesel	X‑TYPE	2001–2009	Ford-sourced 2.0 TDCi
Duratorq 2.2	2.2L	I4 Diesel	X‑TYPE	2004–2009	Ford-sourced 2.2 TDCi
GTDi 2.0	2.0L	I4 Petrol	XF, XJ	2010–2014	EcoBoost-based 2.0 petrol, rare

Codes marked with a suffix (e.g., AJ126‑S) denote higher-power variants. Consult the Engine Fitment Matrix for model-specific configurations.

How to Read a Jaguar Engine Code

Jaguar engine codes follow a logical pattern, but the exact format varies by era and source (engine block stamp vs VIN).

VIN Position 8 – Modern Jaguars (2000+)

In the 17‑digit VIN, position 8 is the engine code letter. For example, in SAJAA2024C... the engine code is A, which maps to the 204DTD. The VIN decoder is the most reliable way to confirm the factory engine for your chassis.

For most modern Jaguars, the VIN code letters are:

A – 204DTD (2.0L Ingenium diesel)
D – 204PT (2.0L Ingenium petrol)
F – AJ126 (3.0L V6 supercharged)
G – AJ133 (5.0L V8 supercharged)
H – 306DT (3.0L V6 diesel)
J – AJ20D6 (3.0L I6 diesel)

Engine Block Stamp – Physical Location

The engine code is stamped directly into the cylinder block, usually on a machined pad near the front of the block (behind the water pump on V6/V8) or on the rear face adjacent to the bellhousing. On Ingenium 4‑cylinder engines, the code is on a machined pad on the left-hand side of the block below the exhaust manifold.

The stamp is typically 6–8 characters and may include a suffix. For example, AJ133‑S indicates the supercharged high‑output version. A suffix of ‑A or ‑B often denotes a running change (e.g., revised chain tensioners).

Decoding the Family Code

Jaguar engine families are easily recognised by the prefix:

AJ – AJ‑V8 / AJ‑V6 / Ingenium (AJ200, AJ300 series)
DT – Diesel (usually paired with a number, e.g., 204DTD)
PT – Petrol (Ingenium petrol)
XK – Legendary straight‑six
V12 – Classic V12

If you're unsure which engine is in your Jaguar, use our VIN Decoder Tool or check the Full Fitment Matrix.

How to Confirm Your Engine Code on the Vehicle

The most reliable method is the VIN, as documented above. If you need to visually confirm the engine code from the block, here is the location per major family:

Ingenium 2.0 (204DTD/204PT): Machined pad on the left‑hand side of the block, below the exhaust manifold, visible from above on most models.
AJ126 / AJ133 (V6/V8): On the front face of the block, behind the water pump pulley. A mirror and torch are often required to read it clearly.
306DT / 276DT (V6 diesel): Stamped on the rear face of the block, adjacent to the bellhousing, visible from underneath or with a mirror.
AJ‑V8 4.0/4.2: On a machined pad on the front of the block near the timing cover.
XK6 / V12 (classic): Stamped on a pad on the inlet manifold side of the block, often near the distributor.

For detailed location photos, refer to our Engine Number Location Guide. If the stamp is corroded or unreadable, the VIN is your fallback.

Common Mistakes When Decoding Jaguar Engines

Confusing 204DTD (diesel) with 204PT (petrol). They are completely different engines – the code suffix matters. A quick check of the fuel filler cap will confirm.
Assuming all AJ126 engines are the same. The AJ126 has multiple power outputs (340PS, 380PS, 400PS) and the block stamp often includes a suffix to indicate the tune.
Misreading the VIN. Position 8 is the engine code, but some online decoders use position 7. Always verify against Jaguar's own VIN lookup.
Using aftermarket parts catalogues as a definitive reference. They often omit running changes and late‑production variants. Cross‑check with the engine code decoder and a Jaguar specialist.

Validation – Check Your Engine Code

If you know your engine code and want to confirm the fitment details, enter it below. This tool checks against the proprietary EnginesMarket database of 9,000+ verified UK enquiries [EM-VERIFIED].

Engine Code Check

Enter your engine code (e.g., AJ126, 204DTD):

Check

Not sure? Use our VIN Decoder first to find the correct code.

This validation tool is a free utility provided as part of the Jaguar Ownership Guide. For a full diagnostic assessment, please consult one of our vetted specialists.

Every Figure SourcedOEM workshop data, cross‑checked with proprietary enquiry logs.

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Last Verified March 2026Reviewed on a regular schedule, not left to go stale.

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15+ Vetted Jaguar SpecialistsReal workshop insight behind the caveats, not just the spec sheet.

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Jaguar Engine Code Decoder & List

Full Jaguar Engine Code Decoder Table

How to Read a Jaguar Engine Code

VIN Position 8 – Modern Jaguars (2000+)

Engine Block Stamp – Physical Location

Decoding the Family Code

How to Confirm Your Engine Code on the Vehicle

Common Mistakes When Decoding Jaguar Engines

Validation – Check Your Engine Code

Need to Verify Your Engine Before Booking?

Full Jaguar Engine Code Decoder Table

How to Read a Jaguar Engine Code

VIN Position 8 – Modern Jaguars (2000+)

Engine Block Stamp – Physical Location

Decoding the Family Code

How to Confirm Your Engine Code on the Vehicle

Common Mistakes When Decoding Jaguar Engines

Validation – Check Your Engine Code

Related Specifications

Engine Fitment Matrix →

Engine Number Location →

Engine Failure Index 2026 →

VIN Decoder Tool →

204DTD Oil Capacity →

AJ126 Oil Capacity →

Need to Verify Your Engine Before Booking?