P0123: How to Diagnose & Fix — Throttle/Pedal Position Sensor/Switch 'A' Circuit High Input
4 vehicles · 3 makes · $50-$800 repair
How to diagnose and fix P0123: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Volvo S40 · 2004–2011
The electronic throttle module (ETM) on S40/V50 models with the 2.4L non-turbo (B5244S) engines can fail, setting throttle faults. The ETM controls the throttle blade electronically, and when it fails, the engine enters limp mode with severely limited power or refuses to rev above idle. Volvo's 10-year/200,000-mile Electronic Throttle System warranty extension applied to 1999-2002 P2/P80 models, not to the 2004+ S40/V50. The ETM failure is distinct from the P2 platform (older S60/V70) ETM issue but has similar symptoms.
Common Symptoms
- Check engine light with throttle position codes (P0121, P0122, P0123)
- Engine enters limp mode with limited power
- Engine won't rev above 2,000-2,500 RPM
- Hesitation or surging during acceleration
- Engine stalling at idle
How to Fix
Replace the electronic throttle module (ETM). Updated Volvo part 30711552 or 31216665 depending on engine type. Bosch aftermarket units are also available. Clear fault codes after replacement and perform throttle body adaptation using VIDA diagnostic tool. Note that Volvo's 10-year Electronic Throttle System warranty extension covered 1999-2002 P2/P80 models, not this S40. The repair is straightforward - the ETM bolts to the intake manifold and can be replaced in under an hour.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Volvo 31216327 non-turbo five-cylinder throttle body
replace a scan-data-confirmed internal throttle-body failure on the non-turbo gasoline branch Fitment/availability: Applicable Volvo S40 P1 non-turbo five-cylinder gasoline branch using OE 31216327; confirm VIN, engine code and installed…
- Genuine Volvo 30711552 T5 fuel-injection throttle body
replace a scan-data-confirmed internal T5 throttle-body failure after boost-control and wiring faults are excluded Fitment/availability: Applicable 2004.5-2011 Volvo S40 P1 T5 gasoline branch using OE 30711552; confirm VIN, B5254T engine…
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Sources for this issue (2)
Volvo S60 · 2001–2002
The 2001-2002 S60 (and other P2 platform Volvos) is notorious for ETM failure due to a design flaw in the throttle body electronics. The module develops internal solder joint cracks and corroded contacts, causing the car to enter limp mode, stall at idle, or refuse to accelerate. Volvo issued an extended warranty covering ETMs up to 10 years/200,000 miles on the 2001 S60 and the non-turbo 2002 S60, but many are now beyond that coverage.
Common Symptoms
- Check engine light with reduced engine power message
- Car enters limp mode (limited to ~30 mph)
- Stalling at idle or low speed
- Rough or surging idle
- Throttle unresponsive or delayed
How to Fix
Replace the ETM unit. Genuine Volvo replacement units have an updated design. Aftermarket options from Bosch are also available. Some specialists offer ETM rebuild services. Always reset the throttle adaptation values after replacement using a Volvo-compatible scanner (VIDA/DiCE).
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- XeMODeX VO.1020 pre-programmed contactless Volvo electronic throttle module
replace a scan-data-confirmed internal early ETM sensor failure with a VIN-preprogrammed contactless unit Fitment/availability: 2001 Volvo S60 Turbo and applicable 2001-2002 S60 non-turbo Magneti Marelli ETM branch; VIN and original-modu…
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Sources for this issue (4)
Jeep Wrangler · 1997–2006
The throttle-body-mounted TPS wears and produces an erratic voltage signal, causing high/hunting idle, stalling at stops, hesitation or bucking on acceleration, and — on automatics — erratic or harsh shifting. It is a very common TJ driveability complaint and often turns on the check-engine light.
Common Symptoms
- High or hunting idle
- Stalling when coming to a stop
- Hesitation/bucking on acceleration
- Erratic or harsh automatic shifting
- Check-engine light
How to Fix
Confirm with a scan tool (P0121/P0122/P0123) and swap in a quality TPS — Mopar 04874371AC (superseded by 68433984AA) for 1997-2001 TJs, or 05019411AD for 2002-2006 TJs. Owners strongly recommend Mopar, Standard Ignition, or NGK over cheap economy sensors, which frequently fail again. Verify closed-throttle voltage and idle relearn after install.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Omix 17224.04 throttle-position sensorOEMOmix 17224.04
Replace a circuit-tested TPS on the early throttle-body branch Fitment/availability: 1997-2001 Wrangler TJ 2.5L or 4.0L; verify connector and throttle-body/tang geometry before ordering.
- Genuine Mopar 68404428AA throttle-position sensorOEMMopar 68404428AA
Replace a circuit-tested TPS on the later throttle-body branch Fitment/availability: 2002-2006 Wrangler TJ/Unlimited with 2.4L or 4.0L as cataloged; verify VIN and connector.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (2)
Ford Edge · 2007–2014
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P0123 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0123 mean?
P0123 stands for "Throttle/Pedal Position Sensor/Switch 'A' Circuit High Input." This generic code means the PCM detected a higher-than-expected voltage from the throttle position sensor (or accelerator pedal position sensor) 'A' circuit. The computer uses this signal to know throttle/pedal opening for fuel, timing, and electronic throttle control, so an abnormally high reading disrupts those calculations. Symptoms can include erratic idle, hesitation, surging, poor or sudden acceleration, and limp-home mode, making prompt diagnosis important.
What are the most common causes of P0123?
The most common causes of P0123 are: Faulty throttle position sensor, Short to voltage in the TPS signal circuit, Open sensor ground causing high reading, Damaged or corroded TPS connector, Worn throttle body / TPS contacts, Chafed wiring shorting to a power wire, Faulty PCM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0123?
Repair costs for P0123 range from $50 to $800, depending on the vehicle and root cause.
Which vehicles are affected by P0123?
Au7o has documented P0123 across 4 vehicle models from 3 manufacturers: Ford, Jeep, Volvo.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.