P0121 on Volvo: How to Diagnose & Fix

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.

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.

The early S60 sedan, model years 2001 and 2002 (for 2002, only cars with the naturally aspirated engine), was included in NHTSA recall 06V441000, a Vehicle Speed Control campaign Volvo opened on December 29, 2006. Per the recall summary, throttle position sensor irregularities, a dirty throttle housing, and/or inefficient software calibration may cause a warning lamp to light, followed by the onset of limp home mode. The important part for an S60 owner is the consequence NHTSA recorded: this resulted in a high number of vehicles going into limp home mode without need. In other words, the car's own protective strategy was being triggered too readily. Volvo's fix was a recalibration rather than hardware. The campaign covered 170,099 vehicles in total, counting all models included in it.

This is the same ETM failure as on the S70/V70/S80/S60 Volvos of the same era (the first-gen C70 shares the P80 platform with the 850/S70). The first-generation C70 (1999-2005) is most susceptible.

1999 through 2002 V70 wagons fall under NHTSA recall 06V441000. Volvo's filing describes a combination of factors — throttle position sensor irregularities, a dirty throttle housing, and/or inefficient software calibration — that may light a warning lamp and then bring on limp home mode. NHTSA's consequence statement is blunt: this resulted in a high number of vehicles going into the limp home mode without need. For a V70 owner that reads as a wagon that abruptly restricts itself mid-drive with no genuine underlying failure. The campaign is categorized under Vehicle Speed Control and covers 170,099 vehicles campaign-wide across all included models. Owner notification began December 29, 2006, and the remedy is a software update, not a parts replacement.

The drive-by-wire throttle body contacts wear internally. 1999-2002 V70s (late P80 and early P2) are most affected.

The S70 uses a drive-by-wire Electronic Throttle Module (ETM) made by Magneti Marelli. Its throttle position sensors can fail, and Volvo also blamed a dirty throttle housing and software calibration. When the sensor readings stop making sense, the engine computer sets a fault and drops the car into limp-home mode. Volvo said this sometimes happened when it wasn't needed. Owners report uneven idle, stalling, an "ETS" or Check Engine warning, and a throttle that barely responds. In NHTSA's investigation (EA05021), these failures also caused sudden forward lunging at low speed and faltering during high-speed merges. Volvo's warranty data showed limp-mode ETM fault codes on about 4.5% of the vehicles under investigation. In the US and Canada, Volvo extended ETM coverage from 7 years/70,000 miles to 10 years/200,000 miles for 1999-2002 cars. That extension has now expired for every S70. In March 2006, Volvo released a throttle software update, which became the remedy for recall 06V441000.