P0234: Turbocharger or supercharger boost pressure is higher than the engine computer requested

Turbo overboost

Severity: Inspect soon

P0234 means boost pressure went above what the engine computer asked for. Too much boost can damage the engine, so most cars cut power to protect it. KBB advises against continuing to drive, but the car usually limps along in reduced power, so get it checked soon.

It gets more serious if:

Stop: Pull over when safe and stop driving if you hear loud new engine noises, the engine overheats or it misfires heavily. KBB warns that overboost can cause serious engine damage.

Source: how we rate severity

P0234 in short

P0234 means the turbocharger or supercharger made more boost than the engine computer asked for. Common causes are a stuck wastegate, a faulty boost control solenoid or hose, and engine software that sets the code too easily. Most cars cut power to protect the engine, so get it checked soon and stop if it overheats.

A turbocharger uses exhaust flow to push extra air into the engine. A valve called the wastegate lets some exhaust bypass the turbo so boost stays at the level the engine computer wants.

The computer measures boost with a pressure sensor. On the Saab 9-3, for example, it runs this check under full throttle and sets P0234 when boost goes higher than requested.

Too much boost raises cylinder pressure and heat, which can damage the engine. That is why most cars go into reduced-power mode when P0234 sets.

The fault is often in the control side rather than the turbo itself: a wastegate that sticks, a boost control solenoid or its vacuum hose, or a pressure sensor reading wrong. Several makers have also issued software updates for P0234.

Most likely causes

Cause 1: Wastegate sticking closed or corroded
Supported by vehicle data
Why it ranks here
KBB names the wastegate first, and Porsche tells technicians to check each wastegate for smooth movement and corrosion before replacing a turbo.
What would change this
Rises if the wastegate arm is stiff or does not move when commanded. Falls if it moves freely through its full travel.
Cause 2: Boost control solenoid or its hoses
Supported by vehicle data
Why it ranks here
Volkswagen gives a boost control solenoid test for P0234, and Cadillac found a wastegate hose rubbed through by a clamp on the SRX.
What would change this
Rises if a control hose is cracked, off or mis-routed, or the solenoid fails its port test. Falls if hoses and solenoid test good.
How to test the vacuum hoses and intake leaks
Cause 3: Engine computer calibration
Supported by vehicle data
Why it ranks here
Ford, Lexus, Audi, Cadillac and Buick have all issued software updates for P0234. Audi notes the software can set it when nothing is wrong.
What would change this
Rises if a bulletin covers your VIN and no other codes are stored. Falls if a mechanical fault is found.
How to test the engine control module (ecm / pcm)
Cause 4: Boost pressure sensor or its wiring
Common general cause
Why it ranks here
KBB lists boost sensor wiring as a cause. A sensor reading high makes the computer think boost is too high when it is not.
What would change this
Rises if the sensor reads above atmospheric pressure with the engine off. Falls if it matches atmospheric pressure.
Cause 5: Turbocharger fault
Possible — needs testing
Why it ranks here
KBB lists the turbo itself, but GM warns many turbos replaced for P0234 had nothing wrong. Check everything else first.
What would change this
Rises if the wastegate shaft is seized inside the turbo. Falls if the wastegate and controls work.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Read all stored codes and ask a dealer whether your VIN has a software update or bulletin for P0234.
Low riskTool: OBD-II scan tool
- IfA software bulletin applies
  It meansHave the update done.
  Points to: Engine computer calibration
- IfNothing applies
  It meansCheck the sensor reading next.
  Go to step 2
Step 2: With the key on and engine off, compare the boost pressure reading with atmospheric (barometric) pressure on the scan tool.
Low riskTool: OBD-II scan tool
- IfBoost reads well above atmospheric
  It meansThe sensor or its wiring is at fault.
  Points to: Boost pressure sensor or its wiring
- IfThey match
  It meansInspect the boost control hoses and solenoid.
  Go to step 3
Step 3: Inspect the hoses between the boost control solenoid and the wastegate actuator for cracks, rubbing or wrong routing, and test the solenoid's ports as the maker describes.
Low riskTool: hand vacuum pump
- IfA hose is damaged or the solenoid fails
  It meansRepair the hose or replace the solenoid.
  Points to: Boost control solenoid or its hoses
- IfHoses and solenoid are fine
  It meansCheck the wastegate.
  Go to step 4
Step 4: With the engine off and cool, check that the wastegate arm moves smoothly through its full travel and is free of corrosion.
Use cautionTool: hand tools
Warning:Turbochargers and exhaust parts get extremely hot. Let the engine cool fully first.
- IfThe wastegate is stiff or corroded but frees up
  It meansThe wastegate is the likely cause.
  Points to: Wastegate sticking closed or corroded
- IfThe wastegate shaft is seized
  It meansThe turbo may need replacing.
  Points to: Turbocharger fault

Symptoms

Check engine light
Reduced power or limp mode
Loud or unusual engine or turbo noise Gets more serious: stop and have it checked.
Engine overheating Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

Step 1: Drive gently and avoid full throttle until the car is checked.
Step 2: Ask a dealer to check your VIN for a P0234 software update.

On your vehicle

Ford

2017 · Escape · 2.0L GTDI
Supported by vehicle data
Ford bulletin 16-0116 covers lack of power with P0234 on early-build 2017 Escapes. Whether it is still current is not verified.
2017 · Fusion · 2.0L GTDI
Supported by vehicle data
Ford bulletin 16-0119 covers the same condition on early-build 2017 Fusions.

16-0116Status unverified
Lack of power with P0234
2017escape · 2.0L GTDI · issued September 7, 2016 · NHTSA 10109034
Ford gives a service procedure for lack of power with P0234 on 2017 Escape and MKC 2.0L EcoBoost built on or before 20-Aug-2016.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
16-0119Status unverified
Lack of power with P0234
2017fusion · 2.0L GTDI · issued September 13, 2016 · NHTSA 10109037
Ford gives a service procedure for lack of power with P0234 on 2017 Fusion and MKZ 2.0L EcoBoost built on or before 31-Aug-2016.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Lexus

2015–2016 · NX
Supported by vehicle data
On the NX 200t, check for the Lexus software update before testing parts.

L-SB-0092-16Status unverified
MIL with P023400 turbocharger overboost
2015–2016nx · issued October 20, 2016 · NHTSA 10132871
Lexus updated the engine computer logic for P0234 on the NX 200t.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Audi

2009–2012 · A4
Supported by vehicle data
Audi says P0234 alone, with no other codes, can be a software false alarm on these models.

A011330Status unverified
MIL on, P0234 overboost
2009–2012a4, a5, q5 · issued September 20, 2013 · NHTSA 10121321
Audi says software can set P0234 on its own when no other codes are stored; it can also have a real cause with power loss.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

All Turbocharging, fuel pressure and EGR codes

P0234 questions

Is it safe to drive with P0234?

Only gently and only to get it checked. Too much boost can damage the engine, which is why most cars cut power. Stop driving if the engine overheats or makes loud new noises.

Does P0234 mean I need a new turbo?

Usually not. GM warns many turbos replaced for these codes were fine. Check for software updates, the boost sensor, control hoses, solenoid and wastegate first.

Sources and review

P0234 code: turbocharger/supercharger overboost condition — Kelley Blue Book (KBB Service Advisor, reviewed by Gary Hardesty)
Saab 9-3 (2008) WIS DTC P0234 00 (ME9): Turbocharger overboost detected — Saab Automobile (Saab WIS, read via saabwisonline.com)
2017 911 Carrera: check wastegates for loss of power or P0234/P0299/P2262 (bulletin 122-H9A7N-09) — Porsche Cars North America / NHTSA , August 18, 2016
2006–2014 2.0T gasoline: N75 boost control solenoid valve diagnosis for P0299 and P0234 (Tech Tip TT 21-10-01) — Volkswagen of America / NHTSA , August 29, 2014
2010 SRX 2.8L turbo: P0101 and P0234, low power, wastegate pressure hose (PIP-4825) — General Motors / NHTSA , August 1, 2010
2017 Escape and MKC 2.0L GTDI: lack of power with MIL and P0234 (TSB 16-0116) — Ford Motor Company / NHTSA , September 7, 2016
2017 Fusion and MKZ 2.0L GTDI: lack of power with MIL and P0234 (TSB 16-0119) — Ford Motor Company / NHTSA , September 13, 2016
2015–2016 NX 200t: MIL with P023400 turbocharger overboost (L-SB-0092-16) — Lexus / NHTSA , October 20, 2016
MIL on, DTC P0234 overboost stored (bulletin A011330, supersedes TSB 12-28) — Audi of America / NHTSA , September 20, 2013
2016 CT6 3.0L twin turbo: ECM reprogram for P0234 (service update 43190) — General Motors / NHTSA , May 4, 2016
2012 Regal GS: reprogram ECM for lack of power, no boost and/or P0234 (PI0849) — General Motors / NHTSA , October 30, 2012
P0299 or P0234: causes of misdiagnosed turbocharger replacement (PIP5495B) — General Motors / NHTSA , June 14, 2017

Last reviewed: October 15, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Inspect soon

Most likely causes

Cause 1: Wastegate sticking closed or corroded

Cause 2: Boost control solenoid or its hoses

Cause 3: Engine computer calibration

Cause 4: Boost pressure sensor or its wiring

Cause 5: Turbocharger fault

What to test first

Step 1: Read all stored codes and ask a dealer whether your VIN has a software update or bulletin for P0234.

Step 2: With the key on and engine off, compare the boost pressure reading with atmospheric (barometric) pressure on the scan tool.

Step 3: Inspect the hoses between the boost control solenoid and the wastegate actuator for cracks, rubbing or wrong routing, and test the solenoid's ports as the maker describes.

Step 4: With the engine off and cool, check that the wastegate arm moves smoothly through its full travel and is free of corrosion.

Symptoms

How to fix

On your vehicle

FordYour car

LexusYour car

AudiYour car

Related codes

P0234 questions

Sources and review

Ford

Lexus

Audi