How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is situated at the top of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).
It's a bit tricky to test since there are several connector pins, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is operating at its maximum. Check for evidence of coolant or oil in the connector bay if you have problems with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power as if the engine was running out of gas or the injectors aren't firing anymore. I took out the spark plugs this morning, 3 were drenched in gasoline and the fourth was dry. When I crank the engine without sparks, I put a piece of tissue on top of each injector hole, the 3 drenched with gazoline pop out, but the 4th one stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero Ohm. I'm assuming the issue is somewhere else.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However, the intermittent misfire problem continues to occur at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil pressure gauge in the cockpit shows 2 bar when the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do, i believe that i've eliminated everything else. However, i'm afraid that i might have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sender is the same as the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local parts store. It is easy to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to more info know both the speed and position of the crankshaft to determine fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either of these sensors, the diagnostic scanner will display codes that could cause an here engine shut down.
A failing G28 sensor could result in an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, or a misfire in the gear. It is probable that the sensor is failing and requires to be replaced if you encounter any of these signs. They're cheap audi spare key and easy to find especially in the case of an Bosch sensor like ours. Alternately, the GM version of this part is also a good choice.
5. Tachometer
A damaged engine sensor could cause a variety of issues in your car. It's an essential component of the transmission in your Audi because it relays information to the ECU about how fast or slowly the engine of the car is spinning. This sensor could cause the transmission to malfunction and other components of the car to be affected.
The G5 engine speed more info sensor is situated on the edge of the transmission above the flywheel ring gear and check here sends a signal to the ECU at pin T55/49 via a grey wire. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. You should see an average resistance of 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 Du, so you might find them in wrecking yards.