P0236: Turbocharger/Supercharger Boost Sensor "A" Circuit Range/Performance

P0236 means the boost pressure sensor is producing a reading that does not make sense to the ECU, even though its voltage is still inside the normal range. The ECU checks it against the barometric and manifold pressure readings with the engine off, and against the boost it expects while driving; when they disagree it sets P0236. A faulty sensor is a common cause, but a boost leak, a contaminated sensing port or a turbo control fault can produce the same code. Most repairs cost between 40 and 200 euros.

P0236 is a fuel system-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0236 and illuminates the check engine light.

If your vehicle has triggered P0236, you may notice one or more of these symptoms:

• Check engine light on
• Reduced power or limp mode, especially under acceleration
• Slow, flat acceleration because the ECU limits boost to a safe substitute value
• Black smoke under load on diesels if fuelling and boost no longer match
• Hissing or whooshing under boost if a charge pipe or intercooler hose is leaking
• Code returns soon after being cleared, often on the first hard acceleration

Here are the most common causes of P0236:

No - address this immediately. Once the ECU stops trusting the boost sensor it usually limits boost and power, and on many turbo diesels and petrols that means limp mode, which can arrive without warning under load. Drive gently to a workshop, avoid heavy throttle, towing and motorway merging at full load, and do not keep driving for weeks on a substitute value.

Follow these steps to pinpoint the root cause of P0236:

1. Read all stored codes and the freeze frame. If P0299 or P0234 is stored as well, boost really did go wrong and the sensor may be reporting it correctly; if P0236 is on its own, the sensor or its wiring is the stronger suspect
2. Switch the ignition on without starting the engine and compare the boost sensor, MAP and barometric readings. With no boost in the system they should all read atmospheric pressure, roughly 95 to 105 kPa at sea level, within a few kPa of each other. A generic OBD2 reader shows these where the ECU exposes them. A boost sensor that reads clearly higher or lower than the other two with the engine off is faulty or has a wiring problem
3. Start the engine and watch the boost reading at idle, then under load on a road test. It should sit near atmospheric at idle and rise smoothly as you accelerate. A reading that jumps, drops out or stays flat while the engine clearly pulls points at the sensor or its connector
4. Remove the sensor and inspect the sensing port and the tip. Oil sludge or soot blocking the port slows or distorts the reading, so clean it and check the charge pipe for heavy oil, which can point at crankcase breather or turbo seal problems
5. Perform a boost leak test by pressurising the intake system with compressed air at 0.5 to 1 bar and listening or using soapy water at every clamp, hose and the intercooler
6. Back-probe the connector with the ignition on. The reference should read about 4.5 to 5.2 V and the sensor ground within about 0.1 V of battery negative. Wiggle the harness while watching the live reading to catch an intermittent fault
7. If the sensor, wiring and boost system all check out, have the wastegate or turbo actuator checked. Actuator tests need manufacturer-level software; a generic OBD2 reader cannot run them

Repair costs for P0236 vary depending on the root cause and your vehicle. Here are typical estimates:

P0236 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

These codes are often seen alongside P0236 or indicate related issues: