The Quick Answer above is the generic definition. What follows is the model-specific detail for the Ford models that log P0238.
DTC/P0238·Ford
P0238 on Ford: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeverityNot safe to driveFord
P0238 on a Ford means the voltage from the boost pressure sensor has risen above the maximum the ECU accepts, typically above about 4.5 to 4.9 V. The ECU reads that as an impossibly high boost pressure, ignores the sensor and usually limits power. Unlike P0234, it does not mean the turbo is really overboosting: it is almost always an electrical fault such as an unplugged or failed sensor, a broken ground or a signal wire shorted to voltage. Most repairs cost between 40 and 220 euros.
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Ford Fiesta ST 1.6 EcoBoost
2013-2018On the Fiesta ST's 1.6 EcoBoost the boost sensor behind this code is the combined turbocharger boost pressure and charge air temperature (TCBP/CACT) sensor in the charge air ducting, not the MAP sensor on the engine. It is reached from under the car and held by a single retainer, and one connector carries both its pressure and its temperature signals, so check that plug first and note whether a charge air temperature code is stored alongside.
What causes P0238 on a Ford?
Beyond the generic causes listed on the main P0238 page, these are the patterns noted for Ford models:
Ford Fiesta ST 1.6 EcoBoostTCBP/CACT connector unplugged, corroded or damaged
Ford Fiesta ST 1.6 EcoBoostFailed TCBP/CACT sensor
How to diagnose P0238 on a Ford with OBD2
Follow these steps to pinpoint the root cause of P0238:
- Read all stored codes. If P0238 sits alongside other high-input sensor codes, suspect a shared 5 V reference or ground rather than the boost sensor itself. If P0234 is also stored, check whether boost was really high before blaming the sensor
- With the ignition on and the engine off, read the live boost value where the ECU exposes it on a generic OBD2 reader, or the MAP reading on engines that share one sensor. With no boost in the system it should read atmospheric pressure, roughly 95 to 105 kPa at sea level. A reading pinned far above that, often at the top of the sensor's range, confirms the signal really is high
- Inspect the sensor and connector. Check that the plug is fully clicked home, look for corrosion, water or oil inside it, and look for pins that have pushed back. Follow the harness for chafing where it runs near the turbo, brackets or the charge pipe
- Unplug the sensor and, with the ignition on, bridge the signal pin to the sensor ground pin at the connector with a fused jumper while watching the live value. If the reading drops to the bottom of the scale and the fault turns into the circuit low code, the signal wire and the ECU are fine, and the sensor or its ground is the problem. If it stays high, the signal wire is shorted to voltage somewhere between the plug and the ECU
- With the sensor plugged back in, back-probe the reference and ground. The reference should read about 4.5 to 5.2 V and the ground within about 0.1 V of battery negative. A reference at battery voltage means a short to 12 V; a ground well above 0.1 V means an open or corroded ground
- Fit the correct sensor for the engine and confirm the reading returns to atmospheric pressure with the key on. Then clear the code and road test, watching the boost value rise smoothly under load
How much does P0238 cost to fix on a Ford? (EUR)
Estimated repair costs for P0238 in EUR, compiled across makes. Ford costs typically sit in the middle of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0238
These codes are often seen alongside P0238 or point to related issues, on any make:
Looking for the full P0238 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0238 guideSkanyx · Ford
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