# OBD Code Guide

> Independent diagnostic reference for OBD-II trouble codes: what the code means,
> whether you can keep driving, how long you have, and what the repair actually costs.
> Written for US drivers, not for mechanics.

## Core sections

- [All OBD codes](https://askmycar.com/obd/): the full code index, P/B/C/U series, one page per code with definition, drivability verdict, causes, diagnostic steps and cost ranges.
- [Repair cost guides](https://askmycar.com/repair-cost/): cost ranges by code and by vehicle, split into shop, dealer and DIY, with the parts list behind each number.
- [Symptom diagnosis](https://askmycar.com/symptoms/): start from what the car is doing (rough idle, shake under load, no start, poor fuel economy) and get the codes that usually produce it.
- [California CARB guides](https://askmycar.com/carb/): CARB-compliant parts, smog check rules, and what actually fails a California emissions test.

## Data methodology

Diagnostic frequencies are computed from NHTSA ODI complaint data, retrieved
monthly and stored per code and per vehicle. Cost ranges are cross-validated
across multiple parts and labor sources; where a field has no verified source it
is left blank instead of estimated. Every page carries the retrieval month and a
last-updated date. Last update: 2026-11.

## About

Maintained by Marcus Feld, an ASE-certified technician with hands-on diagnostic
experience on US-market vehicles. Pages are reviewed against the NHTSA data
before publishing; corrections are made on the page, not in a changelog nobody
reads.