OBD-II trouble code
P0242: Turbocharger/Supercharger Boost Sensor "B" Circuit High
SAE J2012 APR2002: boost sensor B circuit high. On the 2009 GT-R that is an excessively high bank 2 voltage. The printed pair is the sensor after the pressure table fails.
Quick facts
- System
- Powertrain
- Category
- Fuel & Air
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $236 – $273 (turbocharger boost sensor replacement, parts and labor, after the 2009 GT-R bank 2 table fails; a short to power in F30 and bank 1 are outside this pair)
- DIY difficulty
- Intermediate DIY
Browse every code in P0200–P0299, or start from the full code library.
What does P0242 mean?
SAE J2012 APR2002 names P0242 Turbo/Super Charger Boost Sensor "B" Circuit High. Section 3.4 is a characteristic measured at the module pin above the normal operating range, with the external circuit connected. P0241 is the low row on the same letter. An unplugged pin sitting high is not yet this code's measurement.
The 2009 GT-R manual names P0242 turbocharger boost sensor (bank 2) circuit high input: an excessively high voltage from the sensor is sent to the ECM. The harness can be open or shorted, or the sensor can be the failed part. P0643 is diagnosed first when it is stored too. Bank 2 is connector F30. The supply check is still approximately 5 V at terminal 1, key on, sensor disconnected. That check does not by itself prove a circuit-high signal. A supply that is not approximately 5 V is an open, a short to ground, or a short to power, and the manual keeps those three words.
The signal short-to-power check is step 4, ignition off, ECM connector F102 disconnected: continuity from F30 terminal 2 to terminal 79, and a separate look for a short to ground and a short to power. The component table is the same pair of points used for the low code, read the other way. At 10–30°C, terminal 79 against terminal 75 is about 2.03 V at 0 kPa relative and about 2.67 V at +40 kPa. A sensor that will not sit near 2.03 V when the pump is at 0 kPa fails that inspection and is replaced. The table does not contain a 4 V limit, and it does not call 0.5 V a key-on normal. Those figures turn up on aggregator pages and are not this manual.
Bank 1 high is P0238, connector F14, ECM terminal 80. Using terminal 80 for a P0242 repair tests the wrong sensor.
Common causes
- P0643 stored with P0242 on a GT-R, which that manual handles before the pressure part
- A short to power on F30 terminal 2, found with ECM F102 disconnected and the ignition off
- A bank 2 sensor that will not read about 2.03 V at 0 kPa on the published table
- A supply at F30 terminal 1 that is not approximately 5 V, which is still an open, a short to ground, or a short to power
- Bank 1 terminal 80, which is the other sensor on that page
Symptoms
- P0242 stored
- Bank 2 voltage described by the GT-R page as excessively high
- A 0 kPa pump reading well above about 2.03 V after the harness checks pass
- P0643 stored in the same test
- P0241 if the voltage is low instead
Diagnostic steps
- 1.Diagnose P0643 first when the GT-R stores it with P0242.
- 2.Ignition off, ground M95. Then F30 disconnected, ignition on, terminal 1 approximately 5 V. Write the actual miss: open, short to ground, or short to power.
- 3.Ignition off, ECM disconnected. Check F30-2 to F102-79 for continuity, then for a short to power, then for a short to ground. A high voltage seen with the sensor unplugged and the ECM still connected is not this step.
- 4.Pressure-pump at 10–30°C. Terminal 79 to 75 should be about 2.03 V at 0 kPa and about 2.67 V at +40 kPa. Replace the bank 2 sensor when the inspection fails. Do not replace it because an aggregator expected 0.5 V.
- 5.Do not treat a healthy 2.67 V at +40 kPa as circuit high. That point is on the pass table.
- 6.Verify with ignition on for at least 5 seconds, after the manual's 10-second off reset if the confirmation already ran.
Repair cost
$236 – $273 (turbocharger boost sensor replacement, parts and labor, after the 2009 GT-R bank 2 table fails; a short to power in F30 and bank 1 are outside this pair)
RepairPal's turbocharger boost sensor replacement, updated 3 September 2026, is $236–$273 (labor $80–$118, parts around $155). The printed pair is that average for a bank 2 sensor the GT-R inspection replaces. A short to power on terminal 2 is a wiring repair and is outside the pair. Bank 1 is P0238. Diagnosis is $125–$183 labor and is separate. The MAP line of $201–$242 is not this GT-R part.
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DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.