OBD-II Code
C0238
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$300–$2,500
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
C0238 is a circuit-failure code for the hydraulic modulator pump motor inside the ABS hydraulic control unit (HCU) — the EBCM is commanding the pump motor on (to recharge the accumulator during an ABS event or as part of brake-system self-test) and either not seeing the motor draw current, seeing excessive current, or seeing the motor fail to spin up to commanded speed.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureC0238 is a circuit-failure code for the hydraulic modulator pump motor inside the ABS hydraulic control unit (HCU) — the EBCM is commanding the pump…
C0238 is a circuit-failure code for the hydraulic modulator pump motor inside the ABS hydraulic control unit (HCU) — the EBCM is commanding the pump motor on (to recharge the accumulator during an ABS event or as part of brake-system self-test) and either not seeing the motor draw current, seeing excessive current, or seeing the motor fail to spin up to commanded speed. The HCU pump is a brushed DC motor that draws 30-100A momentarily on startup and 10-25A during sustained operation; it lives integrated into the HCU casting on most modern systems, which means a failed pump usually means a full HCU replacement rather than a discrete motor swap.
Cheapest-first ladder
- Scan-tool-actuate the ABS pump motor manually and listen — a healthy pump produces a brief, smooth whirring noise for 1-3 seconds; silence means no motor function (open circuit, failed driver, dead motor brushes); a grinding or labored noise means worn brushes or seized bearings.
- Current-clamp the pump motor power lead during the scan-tool actuation — expect a 30-100A momentary inrush spike followed by a 10-25A running current. Zero current draw is a circuit-side fault; a high stalled current is a mechanically seized pump.
- Check the pump motor relay (separate from the valve relay on most systems) — ohm the coil, swap with a known-good identical relay, and re-test.
- Inspect the motor power feed at the HCU connector for corrosion and the chassis ground point for the EBCM at the body bolt where it's typically mounted. Expensive-misdiagnosis caveat: on Ford F250/F350 SuperDuty with the Hydra-Max hydraulic brake-boost system, C0238 with a 'brake assist failure' message is most often the hydraulic-boost pump (a separate, much higher-displacement pump than a normal ABS pump) failing rather than the ABS modulator pump — the two faults look similar in code form but the parts cost diverges by an order of magnitude ($350 ABS pump vs. $1,800-$2,500 Hydra-Max pump assembly).
Vehicle-specific patterns1999-2007 Ford F-250/F-350 SuperDuty with Hydra-Max hydraulic brake boost throws C0238 from the well-documented Hydra-Max pump failure — the symptom…
- 1999-2007Ford F-250/F-350 SuperDuty with Hydra-Max hydraulic brake boost throws C0238 from the well-documented Hydra-Max pump failure — the symptom escalates from intermittent 'brake assist' messages to a hard pedal and red brake warning light; replacement of the pump-and-reservoir assembly is the durable fix.
- 2001-2010GM Silverado HD/Sierra HD with the Duramax diesel and the GM exhaust-brake-integrated ABS module throws C0238 from corroded pump-motor terminals at the HCU where road salt collects in the wheel-well-mounted module.
- 2003-2008Dodge Ram 2500/3500 with rear-anti-lock-only systems throws C0238 from a failed RWAL pump motor that's part of an integrated HCU/motor pack.
- 2005-2012Mercedes-Benz E-class/S-class with the Sensotronic SBC system throw C0238 from a failed SBC hydraulic unit — Mercedes recalled and capped service costs on many affected VINs, so VIN-coverage check is the first step.
Estimated repair$300 to $2,500.
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