Audi G28: The Good The Bad And The Ugly
How to Replace an audi key G28 Engine Speed Sensor
In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated on the outside of the transmission just above the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, just above the flywheel ring. This sensor repaired sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to control the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu has to be aware of when the crankshaft has reached TDC and also where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).
It is a little tricky to test since there are various pins on the connector, and each one has different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is fully functional, it should read around 1000 ohms. If you are having problems with this sensor, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power as if the engine was running out of gas or the injectors are not firing at all. I pulled out the spark plugs this morning, 3 were drenched in gasoline and the fourth was unclean. I put a piece of tissue over each injector hole, and when i turn the engine on without sparks, the ones that have gazoline pop right out. The 4th one stays closed. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero Ohm. So i assume the problem is elsewhere.
I also tried to reset PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem persists at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.
I'm not sure what to do, i think i've pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or a parts store. Testing them is easy - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black end of the connector). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the position and speed of the crankshaft to make decisions about fuel injector timing etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these sensors go wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, audi keys and/or a misfire while in the gear. If you are experiencing any of these problems, it is likely your sensor is failing and should be replaced. The good news is that they are quite affordable and easily accessible, especially if you're looking at the Bosch model, like ours. Alternatively, GM's version of this part is a good option.
5. Tachometer
A damaged engine sensor could cause a variety of issues in your audi car keys replacement. It's a crucial component of the transmission of your audi a3 key fob because it relays information to the ECU about how fast or slow the engine is spinning. If the sensor fails, it will affect the performance of the transmission and the rest of the car's components.
The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU then processes this signal to control fuel, timig and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. It should show around 1000 ohms of resistance between these two points. This is a common part across the Audi Keyless go 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.