How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission, above the flywheel gear. It sends a message to the ECU via an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through the grey wire. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors accordingly.
If this sensor 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 jumpy chain link in the upper chain of timing. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two connector pins and they perform different functions but the most effective method of testing it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should be reading around 1000 ohms. Check for evidence of coolant or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss as if the engine was running out of gas or injectors aren't firing any more. I pulled out the spark plugs this morning and found that 3 were drenched in gasoline and the 4th was dry. 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 remains shut. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get 0ohm. So i assume the problem is elsewhere.
I also tried to reset the PID but with no luck. The car will start if the G28 is disconnected and runs fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit shows 2 bar when the actual pressure is 0.0 when I crank up the engine.
read here 'm not sure what to do, i think i've pretty much eliminated everything else. I'm afraid i may have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent by 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 measure the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines requires to know both the speed and position of the crankshaft to make decisions regarding 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 goes badly, you will see codes on the diagnostic scanner which could cause engine shut down.
A damaged G28 sensor can cause an inaccurate speed counter for the gearbox, a gearbox that shifts more quickly than normal, or a misfire in gear. It is probable that your sensor is failing and requires to be replaced if you experience any of these symptoms. They're cheap and easy to find, especially in the case of an Bosch model like ours. Alternatively, GM's version of this component is an option.
5. Tachometer
A malfunctioning engine sensor can cause a number of problems in your car. It is a crucial part of the Audi's transmission because it communicates to the ECU about how the car's crankshaft is rotating. If the sensor fails, it could 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 a signal via a gray wire to the ECU pin T55/49. The ECU utilizes this signal to regulate the flow of fuel and boost and also to timigrate. It also transmits it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these points. This is a common part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.