The Three Greatest Moments In Audi G28 History
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated at the top of the transmission just above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through a grey wire. The ECU utilizes this information to control fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails, the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).
Testing is a bit tricky as there are two different pins for the connector and they serve different purposes but the most effective method to test it is to measure the resistance between the sensor and the ECU. It should read around 1000 ohms if the sensor is in full operation. Look for signs of coolant, or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had massive power loss as if the engine was running out of gas or the injectors are not firing anymore. Today, i pulled out the spark plugs, 3 were soaked with gazoline and the fourth one was dry. When i crank the engine, there are no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline jump out but the 4th stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero ohm. So i assume the problem is in another place.
I also tried to reset the PID without success. audi a3 key replacement near me will start when the G28 is disconnected, but 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 it is unplugged, shows an ice temperature of -49c. Also i 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 ruled everything else out. I'm worried that i might have missed something. Please let me know if you have any ideas! 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 they both work in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. It is simple to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes badly, you will see codes on the diagnostic scanner which can cause the engine to shut down.
A failing G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts more quickly than normal, and/or a misfire in the gear. If you have any of these problems, it is most likely that your sensor is going bad and needs replacing. The good news is that they are very affordable and easily accessible particularly in the case of the Bosch unit like ours. Alternatively, GM's version of this part would be a good option.
5. Tachometer
A faulty engine speed sensor could be the reason behind many problems in your car. It's a crucial component of the transmission in your Audi since it sends information to the ECU regarding how fast or slow the engine is spinning. This sensor could cause the transmission to fail and other components in the car to be affected.
The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It sends signals via gray wire to ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also sends it to the G5 Tachometer in instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms between these points. This is a common part that is found across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.