Analysis of 4,801 OBD2 Codes: What Our Database Reveals

1. Powertrain (P) codes make up 79.46% of the base

Out of the 4,801 codes, 3,815 are P codes (engine, transmission, emissions, hybrid), versus 401 B codes (body), 406 U codes (network), and 179 C codes (chassis). This reflects that the OBD-II standard was originally designed to monitor the powertrain, and body, chassis, and network codes arrived much later and are far more manufacturer-specific.

Table 1. Distribution by code letter (P/B/C/U) over the 4,801 unique codes.

Group	Meaning	Codes	Percentage
P	Powertrain (engine, transmission, emissions, hybrid)	3,815	79.46%
U	Network (inter-module communication, CAN bus)	406	8.46%
B	Body (bodywork, airbags, comfort)	401	8.35%
C	Chassis (brakes, suspension, steering)	179	3.73%

2. Severity is mostly Medium and High

Over the subset of B/C/U codes in the batch (2,773) — the only ones that have a severity field assigned in our data —, the distribution is: 1,388 classified as Medium (50.05%), 1,151 as High (41.51%), 180 as Low (6.49%), and 54 as Critical (1.95%). In other words, nearly half are medium severity, and 9 out of 10 fall between medium and high, which is consistent with the nature of B/C/U codes: when one trips, it usually requires attention fairly soon.

⚠️ Honest limitation: the Powertrain codes from the original catalogue (P0000–P0XXX) do not carry a severity column in the CSV we use, which is why this table is computed only over the 2,773 codes in the batch. We do not extrapolate the percentage to the total of 4,801 because there is no data to support it.

Table 2. Severity distribution over the 2,773 batch codes with the field assigned.

Severity	Codes	Percentage (of 2,773)
Medium	1,388	50.05%
High	1,151	41.51%
Low	180	6.49%
Critical	54	1.95%

3. Fuel and Emissions (P2xxx) is the most documented sub-system

Applying the numeric-range SAE classifier (the same tool that organises our thematic hubs), the most documented sub-system is fuel and emissions (P2xxx range), with 1,183 codes (24.64% of the total). It is followed by the hybrid and electric system (P0Axx–P0Cxx) with 645 (13.43%), and fuel and air induction (P00xx–P02xx) with 560 (11.66%). The least documented sub-system is ignition (P3xxx), with 100 codes (2.08%).

Table 3. Codes per sub-system (classifier clasificar_subsistema.py) over the 4,801 unique codes.

Sub-system	SAE range	Codes	%
Fuel and Emissions (extra)	P2xxx	1,183	24.64%
Hybrid and Electric	P0Axx–P0Cxx	645	13.43%
Fuel and Air Induction	P00xx–P02xx	560	11.66%
Transmission	P07xx–P09xx	430	8.96%
Network / Communication	U0xxx, U1xxx, U3xxx	406	8.46%
Body	entire B-code	401	8.35%
Manufacturer-Specific	P1xxx	283	5.89%
Computer and Circuits	P06xx	210	4.37%
Chassis	entire C-code	179	3.73%
Emission Controls	P04xx	171	3.56%
Speed and Idle	P05xx	126	2.62%
Ignition and Misfires	P03xx	107	2.23%
Ignition (extra)	P3xxx	100	2.08%

4. Ford dominates among flagged manufacturers: 28.42% of the batch with a make

Of the 2,773 rows in the B/C/U batch (all have a marca_asociada assigned, never empty), the concrete make that appears in most codes — counting each make individually, because a row can list several — is Ford, with 788 appearances (28.42%), very closely followed by Lincoln (774, 27.91%) and Mercury (631, 22.76%). The reason the three appear nearly paired is that historically Ford Motor Company bundles all three brands onto the same electronic diagnostic platform, so a single B/C/U code typically applies to Ford, Lincoln, and Mercury simultaneously. Taking the three as the Ford family, that family shows up in 788 rows (the rows explicitly listing Ford), i.e. nearly 3 out of every 10 entries with a known make in the batch.

Reading note: Todas las marcas compatibles con OBD-II (all OBD-II-compatible makes) is a special value we assign to generic codes (any manufacturer). That label appears in 1,740 rows (62.75% of the batch). Ford's 28.42% figure is computed over the 2,773 total rows of the with-make batch.

Note: this 788 figure counts every Ford/Lincoln/Mercury appearance in the batch, including codes that also mention other competing makes (e.g. GM, Chrysler) in the same field. The dedicated Ford, Lincoln, Mercury hub excludes those mixed cases and groups 770 codes exclusive to the Ford family — that is the recommended figure if you want to browse only Ford codes.

Table 4. Top 8 individual makes most frequent in the marca_asociada field (B/C/U batch, 2,773 rows).

Individual make	Appearances	% of batch (2,773)
All OBD-II makes (generic)	1,740	62.75%
Ford	788	28.42%
Lincoln	774	27.91%
Mercury	631	22.76%
Mazda	117	4.22%
Toyota	86	3.10%
Lexus	86	3.10%
General Motors (Chevrolet, etc.)	45	1.62%

5. Only 5.89% of the base are manufacturer-specific codes (P1xxx)

When people spot a P code, it is almost always a standard SAE generic: 3,532 codes (73.57%) of the entire base fall in the P0xxx, P2xxx, or P3xxx ranges, which are defined by the SAE J2012 standard itself and apply to any make. In contrast, only 283 codes (5.89%) are in the P1xxx range, reserved by the standard for manufacturer-specific definitions — those that only make sense within the make that defined them. The near-total absence of P1xxx duplicates between manufacturers in our base is consistent with this: the range is designed so brands don't collide.

Table 5. Standard SAE generic vs manufacturer-specific Powertrain codes, over the 4,801 unique codes.

Powertrain type	Ranges	Codes	% of 4,801
Standard SAE generic	P0xxx, P2xxx, P3xxx	3,532	73.57%
Manufacturer-specific	P1xxx	283	5.89%