Will P0123 clear itself if I just drive it?

No. It's a hard electrical fault. The MIL might go out after several drive cycles without the fault recurring, but the underlying wiring or sensor issue almost always comes back within minutes.

Will P0123 make my car fail an emissions inspection?

It can. The engine warning light and the OBD reading are checked at the periodic inspection in most EU countries, and a stored powertrain code can be recorded as a deficiency, which may result in a failed inspection; each country applies its own rules. Repair it before you book.

Do I need a new throttle body or just the sensor?

On older cable-throttle cars (mostly pre-2005) the TPS is a bolt-on part costing roughly €40-180. On drive-by-wire systems the sensor is integrated into the throttle body and you replace the whole assembly.

Why did my car go into limp mode with this code?

The PCM can't trust the throttle signal, so it ignores the pedal and switches to a failsafe that limits throttle opening or engine speed to prevent unintended acceleration. How far it limits power varies by manufacturer.

Do I need to relearn the throttle after replacing it?

Yes, on nearly all drive-by-wire cars. Most brands need a specific idle or throttle relearn (Toyota, Honda, VW and BMW all have their own), and on VW and BMW that adaptation needs manufacturer-level software. Skipping it leaves a rough idle even after a good part is fitted.

P0123: Throttle/Pedal Position Sensor/Switch A Circuit High Input

Quick Answer

Not safe to drive

P0123 means the ECU sees TPS 'A' signal voltage above the upper threshold (typically 4.8V of the 5V reference). The computer ignores the throttle input and falls back to limp mode.

Severity: Moderate · Electrical

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What does P0123 mean?

P0123 is a electrical-related diagnostic trouble code classified as moderate severity.

Where it is on the car

Air filter box
Mass airflow sensor (MAF)
Throttle body and throttle position sensor
Intake manifold and MAP sensor
Engine (cylinder head)

What are the symptoms of P0123?

Check Engine Light on, often with a throttle or wrench warning
Reduced engine power (limp mode): the ECU limits throttle opening or engine speed, and how hard it limits varies by manufacturer
Erratic or hesitant acceleration
Engine surges or hunts at idle
Pedal feels dead - no response above light throttle
Hard starting or immediate stall after start
Cruise control disabled

What causes P0123?

Faulty throttle position sensor (worn resistive track or internal short to the 5V reference)
: high
Corroded or spread pins in the TPS/throttle body connector
: high
TPS signal wire shorted to the 5V reference or to battery voltage
: medium
Open or high-resistance sensor ground circuit
: medium
Failed drive-by-wire throttle body actuator assembly
: low
PCM 5V reference or internal A/D fault
: low

Is it safe to drive with P0123?

No - address this immediately. You can drive short distances, but most vehicles trigger limp mode with reduced throttle response. Sudden power loss is possible, so get it diagnosed before longer trips.

How do you diagnose P0123?

Scan for all stored codes and freeze frame. Note if P0122, P0222 or P2135 are set alongside - that changes the diagnostic path
Key on, engine off: watch TPS1 voltage on the scan tool. Above ~4.8V at closed throttle confirms the fault
Inspect the TPS connector for bent pins, green corrosion, or water intrusion
Backprobe the 5V reference at the TPS - should read 4.9-5.1V. If it reads battery voltage, the reference is shorted
Check sensor ground continuity to battery negative (should be under 0.1Ω, voltage drop under 50mV with key on)
Unplug the TPS. Signal voltage at the ECU pin should drop to near 0V. If it stays high, the signal wire is shorted to voltage between sensor and PCM
If wiring checks out, substitute a known-good TPS or throttle body and recheck
Only after all above, suspect PCM 5V reference or A/D converter failure

How much does P0123 cost to fix?

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Clean and reseat TPS connector, apply dielectric grease	€0–€15	€0–€60	€0–€75	Easy
Replace standalone throttle position sensor (cable throttle)	€40–€180	€40–€120	€80–€300	Easy
Replace complete electronic throttle body (drive-by-wire)	€100–€450	€80–€220	€180–€670	Moderate
Repair TPS wiring harness (short or open circuit)	€20–€90	€90–€260	€110–€350	Moderate
PCM replacement and reprogram	€500–€1400	€150–€350	€650–€1750	Professional

Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.

P0123 on specific vehicles

Volkswagen

VW Golf

2004-2015 (Mk5/Mk6)

1.4 TSI (CAXA/CAVD) and 2.0 TDI (CBEA/CJAA) throttle body connectors can corrode where the harness routes near the coolant flange. Manufacturer-level software shows the two throttle angle sensor values separately, which helps confirm which signal is implausible.

Ford

Ford F-150

2004-2010

5.4L 3V Triton trucks show P0123 with wiper-track wear inside the electronic throttle body.

BMW

BMW 3-Series

2001-2011

The E46 M54 and E90 N52 can log P0123 when the throttle actuator (DK-Motor) potentiometer starts failing. The fix is a complete throttle body, so check the connector and the pedal sensor harness before buying one.

Toyota

Toyota Camry

2002-2011

2AZ-FE and 2GR-FE ETCS-i throttle bodies (22030-28070 / 22030-31010) rarely fail early, but when P0123 appears the internal sensor is usually the culprit. Idle relearn required after cleaning or replacement.

P0123 on Honda

Honda Civic

See Honda-specific causes & cost

Common questions about P0123

Will P0123 clear itself if I just drive it?: No. It's a hard electrical fault. The MIL might go out after several drive cycles without the fault recurring, but the underlying wiring or sensor issue almost always comes back within minutes.
Will P0123 make my car fail an emissions inspection?: It can. The engine warning light and the OBD reading are checked at the periodic inspection in most EU countries, and a stored powertrain code can be recorded as a deficiency, which may result in a failed inspection; each country applies its own rules. Repair it before you book.
Do I need a new throttle body or just the sensor?: On older cable-throttle cars (mostly pre-2005) the TPS is a bolt-on part costing roughly €40-180. On drive-by-wire systems the sensor is integrated into the throttle body and you replace the whole assembly.
Why did my car go into limp mode with this code?: The PCM can't trust the throttle signal, so it ignores the pedal and switches to a failsafe that limits throttle opening or engine speed to prevent unintended acceleration. How far it limits power varies by manufacturer.
Do I need to relearn the throttle after replacing it?: Yes, on nearly all drive-by-wire cars. Most brands need a specific idle or throttle relearn (Toyota, Honda, VW and BMW all have their own), and on VW and BMW that adaptation needs manufacturer-level software. Skipping it leaves a rough idle even after a good part is fitted.

Read our detailed guides

Sources

ricksfreeautorepairadvice.com ricksfreeautorepairadvice.com/idle-relearn-procedure-honda/

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