VAG / Volkswagen Throttle Valve Error Codes P0121, P0122, P0221, P0222, P0638: Diagnosis and Solution

VAG - Magneti Marelli (03F.62)

Throttle Bodies

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Various VAG brands, such as Volkswagen, Audi, Seat, and Skoda use the well-known TSI engines. To ensure that this engine maintains the optimal air/fuel ratio, these cars often used the Magneti Marelli throttle body (usually recognizable by part number 03F) between 2010 and 2015. In this article, we will discuss the most common error codes surrounding the VAG throttle body and offer possible solutions. There are various error codes and malfunctions that often occur with this throttle body.

Common VAG throttle body fault codes

If there are faults in the throttle body (in this case the 03F.62 type from Magneti Marelli), the following fault codes are often generated:

P0121 - Throttle position sensor (G69) / Throttle potentiometer, implausible signal
P0122 - Throttle position sensor (G69), signal too weak
P0221 - Accelerator pedal position sensor 2 / Throttle angle sensor 2 (G188), implausible signal
P0222 - Sensor B Throttle position 2 (G188), signal too weak
P0638 - Throttle valve control cylinder bank 1 (J338), improbable signal

These fault codes clearly indicate that there are problems with the throttle body. An incorrectly functioning throttle body can lead to problems with the air supply and therefore affect the power and efficiency of the engine.

In which cars are these error codes most often read?

These errors are often seen in VAG vehicles with the 1.2 TSI engine with engine code CBZA. The error codes P0121, P0122, P0221, P0222 and P0638 occur in the following models, among others:

Audi A1 8X (2010 - 2018)
Audi A3 8P (2003 - 2012)
Seat Ibiza 6J5, 6J1, 6J8 (2008 - 2017)
Skoda Octavia 1Z (2004 - 2013)
Skoda Rapid NA (2012 - 2020)
Volkswagen Golf VI 5K1, 517, AJ5 (2008 - 2012)
Volkswagen Polo 6R (2009 - 2014)
Volkswagen Touran 1T3 (2010 - 2015)

Symptoms of VAG throttle body error codes P0121, P0122, P0221, P0222 and P0638

Problems with the throttle body will quickly become noticeable through changes in driving behaviour. If there is a disturbance in the air/fuel mixture, the engine malfunction light or the EPC light (Electronic Power Control) will often come on. Other common symptoms of these error codes are:

No response/reaction to accelerator pedal, car only idles
No power, car holds back
Car goes into emergency mode (if the engine is warm)

Solution for these VAG/VW error codes

In many cases, replacing or overhauling the throttle body provides the solution for the aforementioned faults. At ACTRONICS we supply an effective overhaul solution for the Magneti Marelli (03F.62) throttle body, with which the error codes can be cleared and the throttle body functions optimally again. We offer a 2-year warranty on the revision, so you can send your customer on their way again with peace of mind. In consultation, we can often even deliver this part directly from stock. Please contact our customer service first to discuss the possibilities.